import datetime
import os
from decimal import Decimal
from unittest import mock, skipUnless

from django import forms
from django.core.exceptions import (
    NON_FIELD_ERRORS, FieldError, ImproperlyConfigured,
)
from django.core.files.uploadedfile import SimpleUploadedFile
from django.core.validators import ValidationError
from django.db import connection, models
from django.db.models.query import EmptyQuerySet
from django.forms.models import (
    ModelFormMetaclass, construct_instance, fields_for_model, model_to_dict,
    modelform_factory,
)
from django.template import Context, Template
from django.test import SimpleTestCase, TestCase, skipUnlessDBFeature

from .models import (
    Article, ArticleStatus, Author, Author1, Award, BetterWriter, BigInt, Book,
    Category, Character, Colour, ColourfulItem, CustomErrorMessage, CustomFF,
    CustomFieldForExclusionModel, DateTimePost, DerivedBook, DerivedPost,
    Document, ExplicitPK, FilePathModel, FlexibleDatePost, Homepage,
    ImprovedArticle, ImprovedArticleWithParentLink, Inventory,
    NullableUniqueCharFieldModel, Person, Photo, Post, Price, Product,
    Publication, PublicationDefaults, StrictAssignmentAll,
    StrictAssignmentFieldSpecific, Student, StumpJoke, TextFile, Triple,
    Writer, WriterProfile, test_images,
)

if test_images:
    from .models import ImageFile, OptionalImageFile, NoExtensionImageFile

    class ImageFileForm(forms.ModelForm):
        class Meta:
            model = ImageFile
            fields = '__all__'

    class OptionalImageFileForm(forms.ModelForm):
        class Meta:
            model = OptionalImageFile
            fields = '__all__'

    class NoExtensionImageFileForm(forms.ModelForm):
        class Meta:
            model = NoExtensionImageFile
            fields = '__all__'


class ProductForm(forms.ModelForm):
    class Meta:
        model = Product
        fields = '__all__'


class PriceForm(forms.ModelForm):
    class Meta:
        model = Price
        fields = '__all__'


class BookForm(forms.ModelForm):
    class Meta:
        model = Book
        fields = '__all__'


class DerivedBookForm(forms.ModelForm):
    class Meta:
        model = DerivedBook
        fields = '__all__'


class ExplicitPKForm(forms.ModelForm):
    class Meta:
        model = ExplicitPK
        fields = ('key', 'desc',)


class PostForm(forms.ModelForm):
    class Meta:
        model = Post
        fields = '__all__'


class DerivedPostForm(forms.ModelForm):
    class Meta:
        model = DerivedPost
        fields = '__all__'


class CustomWriterForm(forms.ModelForm):
    name = forms.CharField(required=False)

    class Meta:
        model = Writer
        fields = '__all__'


class BaseCategoryForm(forms.ModelForm):
    class Meta:
        model = Category
        fields = '__all__'


class ArticleForm(forms.ModelForm):
    class Meta:
        model = Article
        fields = '__all__'


class RoykoForm(forms.ModelForm):
    class Meta:
        model = Writer
        fields = '__all__'


class ArticleStatusForm(forms.ModelForm):
    class Meta:
        model = ArticleStatus
        fields = '__all__'


class InventoryForm(forms.ModelForm):
    class Meta:
        model = Inventory
        fields = '__all__'


class SelectInventoryForm(forms.Form):
    items = forms.ModelMultipleChoiceField(Inventory.objects.all(), to_field_name='barcode')


class CustomFieldForExclusionForm(forms.ModelForm):
    class Meta:
        model = CustomFieldForExclusionModel
        fields = ['name', 'markup']


class TextFileForm(forms.ModelForm):
    class Meta:
        model = TextFile
        fields = '__all__'


class BigIntForm(forms.ModelForm):
    class Meta:
        model = BigInt
        fields = '__all__'


class ModelFormWithMedia(forms.ModelForm):
    class Media:
        js = ('/some/form/javascript',)
        css = {
            'all': ('/some/form/css',)
        }

    class Meta:
        model = TextFile
        fields = '__all__'


class CustomErrorMessageForm(forms.ModelForm):
    name1 = forms.CharField(error_messages={'invalid': 'Form custom error message.'})

    class Meta:
        fields = '__all__'
        model = CustomErrorMessage


class ModelFormBaseTest(TestCase):
    def test_base_form(self):
        self.assertEqual(list(BaseCategoryForm.base_fields), ['name', 'slug', 'url'])

    def test_no_model_class(self):
        class NoModelModelForm(forms.ModelForm):
            pass
        with self.assertRaisesMessage(ValueError, 'ModelForm has no model class specified.'):
            NoModelModelForm()

    def test_empty_fields_to_fields_for_model(self):
        """
        An argument of fields=() to fields_for_model should return an empty dictionary
        """
        field_dict = fields_for_model(Person, fields=())
        self.assertEqual(len(field_dict), 0)

    def test_empty_fields_on_modelform(self):
        """
        No fields on a ModelForm should actually result in no fields.
        """
        class EmptyPersonForm(forms.ModelForm):
            class Meta:
                model = Person
                fields = ()

        form = EmptyPersonForm()
        self.assertEqual(len(form.fields), 0)

    def test_empty_fields_to_construct_instance(self):
        """
        No fields should be set on a model instance if construct_instance receives fields=().
        """
        form = modelform_factory(Person, fields="__all__")({'name': 'John Doe'})
        self.assertTrue(form.is_valid())
        instance = construct_instance(form, Person(), fields=())
        self.assertEqual(instance.name, '')

    def test_blank_with_null_foreign_key_field(self):
        """
        #13776 -- ModelForm's with models having a FK set to null=False and
        required=False should be valid.
        """
        class FormForTestingIsValid(forms.ModelForm):
            class Meta:
                model = Student
                fields = '__all__'

            def __init__(self, *args, **kwargs):
                super().__init__(*args, **kwargs)
                self.fields['character'].required = False

        char = Character.objects.create(username='user', last_action=datetime.datetime.today())
        data = {'study': 'Engineering'}
        data2 = {'study': 'Engineering', 'character': char.pk}

        # form is valid because required=False for field 'character'
        f1 = FormForTestingIsValid(data)
        self.assertTrue(f1.is_valid())

        f2 = FormForTestingIsValid(data2)
        self.assertTrue(f2.is_valid())
        obj = f2.save()
        self.assertEqual(obj.character, char)

    def test_blank_false_with_null_true_foreign_key_field(self):
        """
        A ModelForm with a model having ForeignKey(blank=False, null=True)
        and the form field set to required=False should allow the field to be
        unset.
        """
        class AwardForm(forms.ModelForm):
            class Meta:
                model = Award
                fields = '__all__'

            def __init__(self, *args, **kwargs):
                super().__init__(*args, **kwargs)
                self.fields['character'].required = False

        character = Character.objects.create(username='user', last_action=datetime.datetime.today())
        award = Award.objects.create(name='Best sprinter', character=character)
        data = {'name': 'Best tester', 'character': ''}  # remove character
        form = AwardForm(data=data, instance=award)
        self.assertTrue(form.is_valid())
        award = form.save()
        self.assertIsNone(award.character)

    def test_save_blank_false_with_required_false(self):
        """
        A ModelForm with a model with a field set to blank=False and the form
        field set to required=False should allow the field to be unset.
        """
        obj = Writer.objects.create(name='test')
        form = CustomWriterForm(data={'name': ''}, instance=obj)
        self.assertTrue(form.is_valid())
        obj = form.save()
        self.assertEqual(obj.name, '')

    def test_save_blank_null_unique_charfield_saves_null(self):
        form_class = modelform_factory(model=NullableUniqueCharFieldModel, fields=['codename'])
        empty_value = '' if connection.features.interprets_empty_strings_as_nulls else None

        form = form_class(data={'codename': ''})
        self.assertTrue(form.is_valid())
        form.save()
        self.assertEqual(form.instance.codename, empty_value)

        # Save a second form to verify there isn't a unique constraint violation.
        form = form_class(data={'codename': ''})
        self.assertTrue(form.is_valid())
        form.save()
        self.assertEqual(form.instance.codename, empty_value)

    def test_missing_fields_attribute(self):
        message = (
            "Creating a ModelForm without either the 'fields' attribute "
            "or the 'exclude' attribute is prohibited; form "
            "MissingFieldsForm needs updating."
        )
        with self.assertRaisesMessage(ImproperlyConfigured, message):
            class MissingFieldsForm(forms.ModelForm):
                class Meta:
                    model = Category

    def test_extra_fields(self):
        class ExtraFields(BaseCategoryForm):
            some_extra_field = forms.BooleanField()

        self.assertEqual(list(ExtraFields.base_fields),
                         ['name', 'slug', 'url', 'some_extra_field'])

    def test_extra_field_model_form(self):
        with self.assertRaisesMessage(FieldError, 'no-field'):
            class ExtraPersonForm(forms.ModelForm):
                """ ModelForm with an extra field """
                age = forms.IntegerField()

                class Meta:
                    model = Person
                    fields = ('name', 'no-field')

    def test_extra_declared_field_model_form(self):
        class ExtraPersonForm(forms.ModelForm):
            """ ModelForm with an extra field """
            age = forms.IntegerField()

            class Meta:
                model = Person
                fields = ('name', 'age')

    def test_extra_field_modelform_factory(self):
        with self.assertRaisesMessage(FieldError, 'Unknown field(s) (no-field) specified for Person'):
            modelform_factory(Person, fields=['no-field', 'name'])

    def test_replace_field(self):
        class ReplaceField(forms.ModelForm):
            url = forms.BooleanField()

            class Meta:
                model = Category
                fields = '__all__'

        self.assertIsInstance(ReplaceField.base_fields['url'], forms.fields.BooleanField)

    def test_replace_field_variant_2(self):
        # Should have the same result as before,
        # but 'fields' attribute specified differently
        class ReplaceField(forms.ModelForm):
            url = forms.BooleanField()

            class Meta:
                model = Category
                fields = ['url']

        self.assertIsInstance(ReplaceField.base_fields['url'], forms.fields.BooleanField)

    def test_replace_field_variant_3(self):
        # Should have the same result as before,
        # but 'fields' attribute specified differently
        class ReplaceField(forms.ModelForm):
            url = forms.BooleanField()

            class Meta:
                model = Category
                fields = []  # url will still appear, since it is explicit above

        self.assertIsInstance(ReplaceField.base_fields['url'], forms.fields.BooleanField)

    def test_override_field(self):
        class WriterForm(forms.ModelForm):
            book = forms.CharField(required=False)

            class Meta:
                model = Writer
                fields = '__all__'

        wf = WriterForm({'name': 'Richard Lockridge'})
        self.assertTrue(wf.is_valid())

    def test_limit_nonexistent_field(self):
        expected_msg = 'Unknown field(s) (nonexistent) specified for Category'
        with self.assertRaisesMessage(FieldError, expected_msg):
            class InvalidCategoryForm(forms.ModelForm):
                class Meta:
                    model = Category
                    fields = ['nonexistent']

    def test_limit_fields_with_string(self):
        expected_msg = "CategoryForm.Meta.fields cannot be a string. Did you mean to type: ('url',)?"
        with self.assertRaisesMessage(TypeError, expected_msg):
            class CategoryForm(forms.ModelForm):
                class Meta:
                    model = Category
                    fields = ('url')  # note the missing comma

    def test_exclude_fields(self):
        class ExcludeFields(forms.ModelForm):
            class Meta:
                model = Category
                exclude = ['url']

        self.assertEqual(list(ExcludeFields.base_fields), ['name', 'slug'])

    def test_exclude_nonexistent_field(self):
        class ExcludeFields(forms.ModelForm):
            class Meta:
                model = Category
                exclude = ['nonexistent']

        self.assertEqual(list(ExcludeFields.base_fields), ['name', 'slug', 'url'])

    def test_exclude_fields_with_string(self):
        expected_msg = "CategoryForm.Meta.exclude cannot be a string. Did you mean to type: ('url',)?"
        with self.assertRaisesMessage(TypeError, expected_msg):
            class CategoryForm(forms.ModelForm):
                class Meta:
                    model = Category
                    exclude = ('url')  # note the missing comma

    def test_exclude_and_validation(self):
        # This Price instance generated by this form is not valid because the quantity
        # field is required, but the form is valid because the field is excluded from
        # the form. This is for backwards compatibility.
        class PriceFormWithoutQuantity(forms.ModelForm):
            class Meta:
                model = Price
                exclude = ('quantity',)

        form = PriceFormWithoutQuantity({'price': '6.00'})
        self.assertTrue(form.is_valid())
        price = form.save(commit=False)
        msg = "{'quantity': ['This field cannot be null.']}"
        with self.assertRaisesMessage(ValidationError, msg):
            price.full_clean()

        # The form should not validate fields that it doesn't contain even if they are
        # specified using 'fields', not 'exclude'.
        class PriceFormWithoutQuantity(forms.ModelForm):
            class Meta:
                model = Price
                fields = ('price',)
        form = PriceFormWithoutQuantity({'price': '6.00'})
        self.assertTrue(form.is_valid())

        # The form should still have an instance of a model that is not complete and
        # not saved into a DB yet.
        self.assertEqual(form.instance.price, Decimal('6.00'))
        self.assertIsNone(form.instance.quantity)
        self.assertIsNone(form.instance.pk)

    def test_confused_form(self):
        class ConfusedForm(forms.ModelForm):
            """ Using 'fields' *and* 'exclude'. Not sure why you'd want to do
            this, but uh, "be liberal in what you accept" and all.
            """
            class Meta:
                model = Category
                fields = ['name', 'url']
                exclude = ['url']

        self.assertEqual(list(ConfusedForm.base_fields),
                         ['name'])

    def test_mixmodel_form(self):
        class MixModelForm(BaseCategoryForm):
            """ Don't allow more than one 'model' definition in the
            inheritance hierarchy.  Technically, it would generate a valid
            form, but the fact that the resulting save method won't deal with
            multiple objects is likely to trip up people not familiar with the
            mechanics.
            """
            class Meta:
                model = Article
                fields = '__all__'
            # MixModelForm is now an Article-related thing, because MixModelForm.Meta
            # overrides BaseCategoryForm.Meta.

        self.assertEqual(
            list(MixModelForm.base_fields),
            ['headline', 'slug', 'pub_date', 'writer', 'article', 'categories', 'status']
        )

    def test_article_form(self):
        self.assertEqual(
            list(ArticleForm.base_fields),
            ['headline', 'slug', 'pub_date', 'writer', 'article', 'categories', 'status']
        )

    def test_bad_form(self):
        # First class with a Meta class wins...
        class BadForm(ArticleForm, BaseCategoryForm):
            pass

        self.assertEqual(
            list(BadForm.base_fields),
            ['headline', 'slug', 'pub_date', 'writer', 'article', 'categories', 'status']
        )

    def test_invalid_meta_model(self):
        class InvalidModelForm(forms.ModelForm):
            class Meta:
                pass  # no model

        # Can't create new form
        msg = 'ModelForm has no model class specified.'
        with self.assertRaisesMessage(ValueError, msg):
            InvalidModelForm()

        # Even if you provide a model instance
        with self.assertRaisesMessage(ValueError, msg):
            InvalidModelForm(instance=Category)

    def test_subcategory_form(self):
        class SubCategoryForm(BaseCategoryForm):
            """ Subclassing without specifying a Meta on the class will use
            the parent's Meta (or the first parent in the MRO if there are
            multiple parent classes).
            """
            pass

        self.assertEqual(list(SubCategoryForm.base_fields), ['name', 'slug', 'url'])

    def test_subclassmeta_form(self):
        class SomeCategoryForm(forms.ModelForm):
            checkbox = forms.BooleanField()

            class Meta:
                model = Category
                fields = '__all__'

        class SubclassMeta(SomeCategoryForm):
            """ We can also subclass the Meta inner class to change the fields
            list.
            """
            class Meta(SomeCategoryForm.Meta):
                exclude = ['url']

        self.assertHTMLEqual(
            str(SubclassMeta()),
            """<tr><th><label for="id_name">Name:</label></th>
<td><input id="id_name" type="text" name="name" maxlength="20" required></td></tr>
<tr><th><label for="id_slug">Slug:</label></th>
<td><input id="id_slug" type="text" name="slug" maxlength="20" required></td></tr>
<tr><th><label for="id_checkbox">Checkbox:</label></th>
<td><input type="checkbox" name="checkbox" id="id_checkbox" required></td></tr>"""
        )

    def test_orderfields_form(self):
        class OrderFields(forms.ModelForm):
            class Meta:
                model = Category
                fields = ['url', 'name']

        self.assertEqual(list(OrderFields.base_fields),
                         ['url', 'name'])
        self.assertHTMLEqual(
            str(OrderFields()),
            """<tr><th><label for="id_url">The URL:</label></th>
<td><input id="id_url" type="text" name="url" maxlength="40" required></td></tr>
<tr><th><label for="id_name">Name:</label></th>
<td><input id="id_name" type="text" name="name" maxlength="20" required></td></tr>"""
        )

    def test_orderfields2_form(self):
        class OrderFields2(forms.ModelForm):
            class Meta:
                model = Category
                fields = ['slug', 'url', 'name']
                exclude = ['url']

        self.assertEqual(list(OrderFields2.base_fields), ['slug', 'name'])

    def test_default_populated_on_optional_field(self):
        class PubForm(forms.ModelForm):
            mode = forms.CharField(max_length=255, required=False)

            class Meta:
                model = PublicationDefaults
                fields = ('mode',)

        # Empty data uses the model field default.
        mf1 = PubForm({})
        self.assertEqual(mf1.errors, {})
        m1 = mf1.save(commit=False)
        self.assertEqual(m1.mode, 'di')
        self.assertEqual(m1._meta.get_field('mode').get_default(), 'di')

        # Blank data doesn't use the model field default.
        mf2 = PubForm({'mode': ''})
        self.assertEqual(mf2.errors, {})
        m2 = mf2.save(commit=False)
        self.assertEqual(m2.mode, '')

    def test_default_not_populated_on_optional_checkbox_input(self):
        class PubForm(forms.ModelForm):
            class Meta:
                model = PublicationDefaults
                fields = ('active',)

        # Empty data doesn't use the model default because CheckboxInput
        # doesn't have a value in HTML form submission.
        mf1 = PubForm({})
        self.assertEqual(mf1.errors, {})
        m1 = mf1.save(commit=False)
        self.assertIs(m1.active, False)
        self.assertIsInstance(mf1.fields['active'].widget, forms.CheckboxInput)
        self.assertIs(m1._meta.get_field('active').get_default(), True)

    def test_default_not_populated_on_checkboxselectmultiple(self):
        class PubForm(forms.ModelForm):
            mode = forms.CharField(required=False, widget=forms.CheckboxSelectMultiple)

            class Meta:
                model = PublicationDefaults
                fields = ('mode',)

        # Empty data doesn't use the model default because an unchecked
        # CheckboxSelectMultiple doesn't have a value in HTML form submission.
        mf1 = PubForm({})
        self.assertEqual(mf1.errors, {})
        m1 = mf1.save(commit=False)
        self.assertEqual(m1.mode, '')
        self.assertEqual(m1._meta.get_field('mode').get_default(), 'di')

    def test_default_not_populated_on_selectmultiple(self):
        class PubForm(forms.ModelForm):
            mode = forms.CharField(required=False, widget=forms.SelectMultiple)

            class Meta:
                model = PublicationDefaults
                fields = ('mode',)

        # Empty data doesn't use the model default because an unselected
        # SelectMultiple doesn't have a value in HTML form submission.
        mf1 = PubForm({})
        self.assertEqual(mf1.errors, {})
        m1 = mf1.save(commit=False)
        self.assertEqual(m1.mode, '')
        self.assertEqual(m1._meta.get_field('mode').get_default(), 'di')

    def test_prefixed_form_with_default_field(self):
        class PubForm(forms.ModelForm):
            prefix = 'form-prefix'

            class Meta:
                model = PublicationDefaults
                fields = ('mode',)

        mode = 'de'
        self.assertNotEqual(mode, PublicationDefaults._meta.get_field('mode').get_default())

        mf1 = PubForm({'form-prefix-mode': mode})
        self.assertEqual(mf1.errors, {})
        m1 = mf1.save(commit=False)
        self.assertEqual(m1.mode, mode)

    def test_renderer_kwarg(self):
        custom = object()
        self.assertIs(ProductForm(renderer=custom).renderer, custom)

    def test_default_splitdatetime_field(self):
        class PubForm(forms.ModelForm):
            datetime_published = forms.SplitDateTimeField(required=False)

            class Meta:
                model = PublicationDefaults
                fields = ('datetime_published',)

        mf1 = PubForm({})
        self.assertEqual(mf1.errors, {})
        m1 = mf1.save(commit=False)
        self.assertEqual(m1.datetime_published, datetime.datetime(2000, 1, 1))

        mf2 = PubForm({'datetime_published_0': '2010-01-01', 'datetime_published_1': '0:00:00'})
        self.assertEqual(mf2.errors, {})
        m2 = mf2.save(commit=False)
        self.assertEqual(m2.datetime_published, datetime.datetime(2010, 1, 1))

    def test_default_filefield(self):
        class PubForm(forms.ModelForm):
            class Meta:
                model = PublicationDefaults
                fields = ('file',)

        mf1 = PubForm({})
        self.assertEqual(mf1.errors, {})
        m1 = mf1.save(commit=False)
        self.assertEqual(m1.file.name, 'default.txt')

        mf2 = PubForm({}, {'file': SimpleUploadedFile('name', b'foo')})
        self.assertEqual(mf2.errors, {})
        m2 = mf2.save(commit=False)
        self.assertEqual(m2.file.name, 'name')

    def test_default_selectdatewidget(self):
        class PubForm(forms.ModelForm):
            date_published = forms.DateField(required=False, widget=forms.SelectDateWidget)

            class Meta:
                model = PublicationDefaults
                fields = ('date_published',)

        mf1 = PubForm({})
        self.assertEqual(mf1.errors, {})
        m1 = mf1.save(commit=False)
        self.assertEqual(m1.date_published, datetime.date.today())

        mf2 = PubForm({'date_published_year': '2010', 'date_published_month': '1', 'date_published_day': '1'})
        self.assertEqual(mf2.errors, {})
        m2 = mf2.save(commit=False)
        self.assertEqual(m2.date_published, datetime.date(2010, 1, 1))


class FieldOverridesByFormMetaForm(forms.ModelForm):
    class Meta:
        model = Category
        fields = ['name', 'url', 'slug']
        widgets = {
            'name': forms.Textarea,
            'url': forms.TextInput(attrs={'class': 'url'})
        }
        labels = {
            'name': 'Title',
        }
        help_texts = {
            'slug': 'Watch out! Letters, numbers, underscores and hyphens only.',
        }
        error_messages = {
            'slug': {
                'invalid': (
                    "Didn't you read the help text? "
                    "We said letters, numbers, underscores and hyphens only!"
                )
            }
        }
        field_classes = {
            'url': forms.URLField,
        }


class TestFieldOverridesByFormMeta(SimpleTestCase):
    def test_widget_overrides(self):
        form = FieldOverridesByFormMetaForm()
        self.assertHTMLEqual(
            str(form['name']),
            '<textarea id="id_name" rows="10" cols="40" name="name" maxlength="20" required></textarea>',
        )
        self.assertHTMLEqual(
            str(form['url']),
            '<input id="id_url" type="text" class="url" name="url" maxlength="40" required>',
        )
        self.assertHTMLEqual(
            str(form['slug']),
            '<input id="id_slug" type="text" name="slug" maxlength="20" required>',
        )

    def test_label_overrides(self):
        form = FieldOverridesByFormMetaForm()
        self.assertHTMLEqual(
            str(form['name'].label_tag()),
            '<label for="id_name">Title:</label>',
        )
        self.assertHTMLEqual(
            str(form['url'].label_tag()),
            '<label for="id_url">The URL:</label>',
        )
        self.assertHTMLEqual(
            str(form['slug'].label_tag()),
            '<label for="id_slug">Slug:</label>',
        )

    def test_help_text_overrides(self):
        form = FieldOverridesByFormMetaForm()
        self.assertEqual(
            form['slug'].help_text,
            'Watch out! Letters, numbers, underscores and hyphens only.',
        )

    def test_error_messages_overrides(self):
        form = FieldOverridesByFormMetaForm(data={
            'name': 'Category',
            'url': 'http://www.example.com/category/',
            'slug': '!%#*@',
        })
        form.full_clean()

        error = [
            "Didn't you read the help text? "
            "We said letters, numbers, underscores and hyphens only!",
        ]
        self.assertEqual(form.errors, {'slug': error})

    def test_field_type_overrides(self):
        form = FieldOverridesByFormMetaForm()
        self.assertIs(Category._meta.get_field('url').__class__, models.CharField)
        self.assertIsInstance(form.fields['url'], forms.URLField)


class IncompleteCategoryFormWithFields(forms.ModelForm):
    """
    A form that replaces the model's url field with a custom one. This should
    prevent the model field's validation from being called.
    """
    url = forms.CharField(required=False)

    class Meta:
        fields = ('name', 'slug')
        model = Category


class IncompleteCategoryFormWithExclude(forms.ModelForm):
    """
    A form that replaces the model's url field with a custom one. This should
    prevent the model field's validation from being called.
    """
    url = forms.CharField(required=False)

    class Meta:
        exclude = ['url']
        model = Category


class ValidationTest(SimpleTestCase):
    def test_validates_with_replaced_field_not_specified(self):
        form = IncompleteCategoryFormWithFields(data={'name': 'some name', 'slug': 'some-slug'})
        assert form.is_valid()

    def test_validates_with_replaced_field_excluded(self):
        form = IncompleteCategoryFormWithExclude(data={'name': 'some name', 'slug': 'some-slug'})
        assert form.is_valid()

    def test_notrequired_overrides_notblank(self):
        form = CustomWriterForm({})
        assert form.is_valid()


class UniqueTest(TestCase):
    """
    unique/unique_together validation.
    """
    def setUp(self):
        self.writer = Writer.objects.create(name='Mike Royko')

    def test_simple_unique(self):
        form = ProductForm({'slug': 'teddy-bear-blue'})
        self.assertTrue(form.is_valid())
        obj = form.save()
        form = ProductForm({'slug': 'teddy-bear-blue'})
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['slug'], ['Product with this Slug already exists.'])
        form = ProductForm({'slug': 'teddy-bear-blue'}, instance=obj)
        self.assertTrue(form.is_valid())

    def test_unique_together(self):
        """ModelForm test of unique_together constraint"""
        form = PriceForm({'price': '6.00', 'quantity': '1'})
        self.assertTrue(form.is_valid())
        form.save()
        form = PriceForm({'price': '6.00', 'quantity': '1'})
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['__all__'], ['Price with this Price and Quantity already exists.'])

    def test_unique_together_exclusion(self):
        """
        Forms don't validate unique_together constraints when only part of the
        constraint is included in the form's fields. This allows using
        form.save(commit=False) and then assigning the missing field(s) to the
        model instance.
        """
        class BookForm(forms.ModelForm):
            class Meta:
                model = DerivedBook
                fields = ('isbn', 'suffix1')

        # The unique_together is on suffix1/suffix2 but only suffix1 is part
        # of the form. The fields must have defaults, otherwise they'll be
        # skipped by other logic.
        self.assertEqual(DerivedBook._meta.unique_together, (('suffix1', 'suffix2'),))
        for name in ('suffix1', 'suffix2'):
            with self.subTest(name=name):
                field = DerivedBook._meta.get_field(name)
                self.assertEqual(field.default, 0)

        # The form fails validation with "Derived book with this Suffix1 and
        # Suffix2 already exists." if the unique_together validation isn't
        # skipped.
        DerivedBook.objects.create(isbn='12345')
        form = BookForm({'isbn': '56789', 'suffix1': '0'})
        self.assertTrue(form.is_valid(), form.errors)

    def test_multiple_field_unique_together(self):
        """
        When the same field is involved in multiple unique_together
        constraints, we need to make sure we don't remove the data for it
        before doing all the validation checking (not just failing after
        the first one).
        """
        class TripleForm(forms.ModelForm):
            class Meta:
                model = Triple
                fields = '__all__'

        Triple.objects.create(left=1, middle=2, right=3)

        form = TripleForm({'left': '1', 'middle': '2', 'right': '3'})
        self.assertFalse(form.is_valid())

        form = TripleForm({'left': '1', 'middle': '3', 'right': '1'})
        self.assertTrue(form.is_valid())

    @skipUnlessDBFeature('supports_nullable_unique_constraints')
    def test_unique_null(self):
        title = 'I May Be Wrong But I Doubt It'
        form = BookForm({'title': title, 'author': self.writer.pk})
        self.assertTrue(form.is_valid())
        form.save()
        form = BookForm({'title': title, 'author': self.writer.pk})
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['__all__'], ['Book with this Title and Author already exists.'])
        form = BookForm({'title': title})
        self.assertTrue(form.is_valid())
        form.save()
        form = BookForm({'title': title})
        self.assertTrue(form.is_valid())

    def test_inherited_unique(self):
        title = 'Boss'
        Book.objects.create(title=title, author=self.writer, special_id=1)
        form = DerivedBookForm({'title': 'Other', 'author': self.writer.pk, 'special_id': '1', 'isbn': '12345'})
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['special_id'], ['Book with this Special id already exists.'])

    def test_inherited_unique_together(self):
        title = 'Boss'
        form = BookForm({'title': title, 'author': self.writer.pk})
        self.assertTrue(form.is_valid())
        form.save()
        form = DerivedBookForm({'title': title, 'author': self.writer.pk, 'isbn': '12345'})
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['__all__'], ['Book with this Title and Author already exists.'])

    def test_abstract_inherited_unique(self):
        title = 'Boss'
        isbn = '12345'
        DerivedBook.objects.create(title=title, author=self.writer, isbn=isbn)
        form = DerivedBookForm({
            'title': 'Other', 'author': self.writer.pk, 'isbn': isbn,
            'suffix1': '1', 'suffix2': '2',
        })
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['isbn'], ['Derived book with this Isbn already exists.'])

    def test_abstract_inherited_unique_together(self):
        title = 'Boss'
        isbn = '12345'
        DerivedBook.objects.create(title=title, author=self.writer, isbn=isbn)
        form = DerivedBookForm({
            'title': 'Other',
            'author': self.writer.pk,
            'isbn': '9876',
            'suffix1': '0',
            'suffix2': '0'
        })
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(
            form.errors['__all__'],
            ['Derived book with this Suffix1 and Suffix2 already exists.'],
        )

    def test_explicitpk_unspecified(self):
        """Test for primary_key being in the form and failing validation."""
        form = ExplicitPKForm({'key': '', 'desc': ''})
        self.assertFalse(form.is_valid())

    def test_explicitpk_unique(self):
        """Ensure keys and blank character strings are tested for uniqueness."""
        form = ExplicitPKForm({'key': 'key1', 'desc': ''})
        self.assertTrue(form.is_valid())
        form.save()
        form = ExplicitPKForm({'key': 'key1', 'desc': ''})
        self.assertFalse(form.is_valid())
        if connection.features.interprets_empty_strings_as_nulls:
            self.assertEqual(len(form.errors), 1)
            self.assertEqual(form.errors['key'], ['Explicit pk with this Key already exists.'])
        else:
            self.assertEqual(len(form.errors), 3)
            self.assertEqual(form.errors['__all__'], ['Explicit pk with this Key and Desc already exists.'])
            self.assertEqual(form.errors['desc'], ['Explicit pk with this Desc already exists.'])
            self.assertEqual(form.errors['key'], ['Explicit pk with this Key already exists.'])

    def test_unique_for_date(self):
        p = Post.objects.create(
            title="Django 1.0 is released", slug="Django 1.0",
            subtitle="Finally", posted=datetime.date(2008, 9, 3),
        )
        form = PostForm({'title': "Django 1.0 is released", 'posted': '2008-09-03'})
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['title'], ['Title must be unique for Posted date.'])
        form = PostForm({'title': "Work on Django 1.1 begins", 'posted': '2008-09-03'})
        self.assertTrue(form.is_valid())
        form = PostForm({'title': "Django 1.0 is released", 'posted': '2008-09-04'})
        self.assertTrue(form.is_valid())
        form = PostForm({'slug': "Django 1.0", 'posted': '2008-01-01'})
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['slug'], ['Slug must be unique for Posted year.'])
        form = PostForm({'subtitle': "Finally", 'posted': '2008-09-30'})
        self.assertFalse(form.is_valid())
        self.assertEqual(form.errors['subtitle'], ['Subtitle must be unique for Posted month.'])
        data = {'subtitle': "Finally", "title": "Django 1.0 is released", "slug": "Django 1.0", 'posted': '2008-09-03'}
        form = PostForm(data, instance=p)
        self.assertTrue(form.is_valid())
        form = PostForm({'title': "Django 1.0 is released"})
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['posted'], ['This field is required.'])

    def test_unique_for_date_in_exclude(self):
        """
        If the date for unique_for_* constraints is excluded from the
        ModelForm (in this case 'posted' has editable=False, then the
        constraint should be ignored.
        """
        class DateTimePostForm(forms.ModelForm):
            class Meta:
                model = DateTimePost
                fields = '__all__'

        DateTimePost.objects.create(
            title="Django 1.0 is released", slug="Django 1.0",
            subtitle="Finally", posted=datetime.datetime(2008, 9, 3, 10, 10, 1),
        )
        # 'title' has unique_for_date='posted'
        form = DateTimePostForm({'title': "Django 1.0 is released", 'posted': '2008-09-03'})
        self.assertTrue(form.is_valid())
        # 'slug' has unique_for_year='posted'
        form = DateTimePostForm({'slug': "Django 1.0", 'posted': '2008-01-01'})
        self.assertTrue(form.is_valid())
        # 'subtitle' has unique_for_month='posted'
        form = DateTimePostForm({'subtitle': "Finally", 'posted': '2008-09-30'})
        self.assertTrue(form.is_valid())

    def test_inherited_unique_for_date(self):
        p = Post.objects.create(
            title="Django 1.0 is released", slug="Django 1.0",
            subtitle="Finally", posted=datetime.date(2008, 9, 3),
        )
        form = DerivedPostForm({'title': "Django 1.0 is released", 'posted': '2008-09-03'})
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['title'], ['Title must be unique for Posted date.'])
        form = DerivedPostForm({'title': "Work on Django 1.1 begins", 'posted': '2008-09-03'})
        self.assertTrue(form.is_valid())
        form = DerivedPostForm({'title': "Django 1.0 is released", 'posted': '2008-09-04'})
        self.assertTrue(form.is_valid())
        form = DerivedPostForm({'slug': "Django 1.0", 'posted': '2008-01-01'})
        self.assertFalse(form.is_valid())
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['slug'], ['Slug must be unique for Posted year.'])
        form = DerivedPostForm({'subtitle': "Finally", 'posted': '2008-09-30'})
        self.assertFalse(form.is_valid())
        self.assertEqual(form.errors['subtitle'], ['Subtitle must be unique for Posted month.'])
        data = {'subtitle': "Finally", "title": "Django 1.0 is released", "slug": "Django 1.0", 'posted': '2008-09-03'}
        form = DerivedPostForm(data, instance=p)
        self.assertTrue(form.is_valid())

    def test_unique_for_date_with_nullable_date(self):
        class FlexDatePostForm(forms.ModelForm):
            class Meta:
                model = FlexibleDatePost
                fields = '__all__'

        p = FlexibleDatePost.objects.create(
            title="Django 1.0 is released", slug="Django 1.0",
            subtitle="Finally", posted=datetime.date(2008, 9, 3),
        )

        form = FlexDatePostForm({'title': "Django 1.0 is released"})
        self.assertTrue(form.is_valid())
        form = FlexDatePostForm({'slug': "Django 1.0"})
        self.assertTrue(form.is_valid())
        form = FlexDatePostForm({'subtitle': "Finally"})
        self.assertTrue(form.is_valid())
        data = {'subtitle': "Finally", "title": "Django 1.0 is released", "slug": "Django 1.0"}
        form = FlexDatePostForm(data, instance=p)
        self.assertTrue(form.is_valid())

    def test_override_unique_message(self):
        class CustomProductForm(ProductForm):
            class Meta(ProductForm.Meta):
                error_messages = {
                    'slug': {
                        'unique': "%(model_name)s's %(field_label)s not unique.",
                    }
                }

        Product.objects.create(slug='teddy-bear-blue')
        form = CustomProductForm({'slug': 'teddy-bear-blue'})
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['slug'], ["Product's Slug not unique."])

    def test_override_unique_together_message(self):
        class CustomPriceForm(PriceForm):
            class Meta(PriceForm.Meta):
                error_messages = {
                    NON_FIELD_ERRORS: {
                        'unique_together': "%(model_name)s's %(field_labels)s not unique.",
                    }
                }

        Price.objects.create(price=6.00, quantity=1)
        form = CustomPriceForm({'price': '6.00', 'quantity': '1'})
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors[NON_FIELD_ERRORS], ["Price's Price and Quantity not unique."])

    def test_override_unique_for_date_message(self):
        class CustomPostForm(PostForm):
            class Meta(PostForm.Meta):
                error_messages = {
                    'title': {
                        'unique_for_date': (
                            "%(model_name)s's %(field_label)s not unique "
                            "for %(date_field_label)s date."
                        ),
                    }
                }

        Post.objects.create(
            title="Django 1.0 is released", slug="Django 1.0",
            subtitle="Finally", posted=datetime.date(2008, 9, 3),
        )
        form = CustomPostForm({'title': "Django 1.0 is released", 'posted': '2008-09-03'})
        self.assertEqual(len(form.errors), 1)
        self.assertEqual(form.errors['title'], ["Post's Title not unique for Posted date."])


class ModelFormBasicTests(TestCase):
    def create_basic_data(self):
        self.c1 = Category.objects.create(name='Entertainment', slug='entertainment', url='entertainment')
        self.c2 = Category.objects.create(name="It's a test", slug='its-test', url='test')
        self.c3 = Category.objects.create(name='Third test', slug='third-test', url='third')
        self.w_royko = Writer.objects.create(name='Mike Royko')
        self.w_woodward = Writer.objects.create(name='Bob Woodward')

    def test_base_form(self):
        self.assertEqual(Category.objects.count(), 0)
        f = BaseCategoryForm()
        self.assertHTMLEqual(
            str(f),
            """<tr><th><label for="id_name">Name:</label></th>
<td><input id="id_name" type="text" name="name" maxlength="20" required></td></tr>
<tr><th><label for="id_slug">Slug:</label></th>
<td><input id="id_slug" type="text" name="slug" maxlength="20" required></td></tr>
<tr><th><label for="id_url">The URL:</label></th>
<td><input id="id_url" type="text" name="url" maxlength="40" required></td></tr>"""
        )
        self.assertHTMLEqual(
            str(f.as_ul()),
            """<li><label for="id_name">Name:</label> <input id="id_name" type="text" name="name" maxlength="20" required></li>
<li><label for="id_slug">Slug:</label> <input id="id_slug" type="text" name="slug" maxlength="20" required></li>
<li><label for="id_url">The URL:</label> <input id="id_url" type="text" name="url" maxlength="40" required></li>"""
        )
        self.assertHTMLEqual(
            str(f["name"]),
            """<input id="id_name" type="text" name="name" maxlength="20" required>""")

    def test_auto_id(self):
        f = BaseCategoryForm(auto_id=False)
        self.assertHTMLEqual(
            str(f.as_ul()),
            """<li>Name: <input type="text" name="name" maxlength="20" required></li>
<li>Slug: <input type="text" name="slug" maxlength="20" required></li>
<li>The URL: <input type="text" name="url" maxlength="40" required></li>"""
        )

    def test_initial_values(self):
        self.create_basic_data()
        # Initial values can be provided for model forms
        f = ArticleForm(
            auto_id=False,
            initial={
                'headline': 'Your headline here',
                'categories': [str(self.c1.id), str(self.c2.id)]
            })
        self.assertHTMLEqual(
            f.as_ul(),
            '''<li>Headline: <input type="text" name="headline" value="Your headline here" maxlength="50" required></li>
<li>Slug: <input type="text" name="slug" maxlength="50" required></li>
<li>Pub date: <input type="text" name="pub_date" required></li>
<li>Writer: <select name="writer" required>
<option value="" selected>---------</option>
<option value="%s">Bob Woodward</option>
<option value="%s">Mike Royko</option>
</select></li>
<li>Article: <textarea rows="10" cols="40" name="article" required></textarea></li>
<li>Categories: <select multiple name="categories">
<option value="%s" selected>Entertainment</option>
<option value="%s" selected>It&#39;s a test</option>
<option value="%s">Third test</option>
</select></li>
<li>Status: <select name="status">
<option value="" selected>---------</option>
<option value="1">Draft</option>
<option value="2">Pending</option>
<option value="3">Live</option>
</select></li>''' % (self.w_woodward.pk, self.w_royko.pk, self.c1.pk, self.c2.pk, self.c3.pk))

        # When the ModelForm is passed an instance, that instance's current values are
        # inserted as 'initial' data in each Field.
        f = RoykoForm(auto_id=False, instance=self.w_royko)
        self.assertHTMLEqual(
            str(f),
            '''<tr><th>Name:</th><td><input type="text" name="name" value="Mike Royko" maxlength="50" required><br>
            <span class="helptext">Use both first and last names.</span></td></tr>'''
        )

        art = Article.objects.create(
            headline='Test article',
            slug='test-article',
            pub_date=datetime.date(1988, 1, 4),
            writer=self.w_royko,
            article='Hello.'
        )
        art_id_1 = art.id

        f = ArticleForm(auto_id=False, instance=art)
        self.assertHTMLEqual(
            f.as_ul(),
            '''<li>Headline: <input type="text" name="headline" value="Test article" maxlength="50" required></li>
<li>Slug: <input type="text" name="slug" value="test-article" maxlength="50" required></li>
<li>Pub date: <input type="text" name="pub_date" value="1988-01-04" required></li>
<li>Writer: <select name="writer" required>
<option value="">---------</option>
<option value="%s">Bob Woodward</option>
<option value="%s" selected>Mike Royko</option>
</select></li>
<li>Article: <textarea rows="10" cols="40" name="article" required>Hello.</textarea></li>
<li>Categories: <select multiple name="categories">
<option value="%s">Entertainment</option>
<option value="%s">It&#39;s a test</option>
<option value="%s">Third test</option>
</select></li>
<li>Status: <select name="status">
<option value="" selected>---------</option>
<option value="1">Draft</option>
<option value="2">Pending</option>
<option value="3">Live</option>
</select></li>''' % (self.w_woodward.pk, self.w_royko.pk, self.c1.pk, self.c2.pk, self.c3.pk))

        f = ArticleForm({
            'headline': 'Test headline',
            'slug': 'test-headline',
            'pub_date': '1984-02-06',
            'writer': str(self.w_royko.pk),
            'article': 'Hello.'
        }, instance=art)
        self.assertEqual(f.errors, {})
        self.assertTrue(f.is_valid())
        test_art = f.save()
        self.assertEqual(test_art.id, art_id_1)
        test_art = Article.objects.get(id=art_id_1)
        self.assertEqual(test_art.headline, 'Test headline')

    def test_m2m_initial_callable(self):
        """
        Regression for #10349: A callable can be provided as the initial value for an m2m field
        """
        self.maxDiff = 1200
        self.create_basic_data()

        # Set up a callable initial value
        def formfield_for_dbfield(db_field, **kwargs):
            if db_field.name == 'categories':
                kwargs['initial'] = lambda: Category.objects.all().order_by('name')[:2]
            return db_field.formfield(**kwargs)

        # Create a ModelForm, instantiate it, and check that the output is as expected
        ModelForm = modelform_factory(
            Article,
            fields=['headline', 'categories'],
            formfield_callback=formfield_for_dbfield,
        )
        form = ModelForm()
        self.assertHTMLEqual(
            form.as_ul(),
            """<li><label for="id_headline">Headline:</label>
<input id="id_headline" type="text" name="headline" maxlength="50" required></li>
<li><label for="id_categories">Categories:</label>
<select multiple name="categories" id="id_categories">
<option value="%d" selected>Entertainment</option>
<option value="%d" selected>It&39;s a test</option>
<option value="%d">Third test</option>
</select></li>"""
            % (self.c1.pk, self.c2.pk, self.c3.pk))

    def test_basic_creation(self):
        self.assertEqual(Category.objects.count(), 0)
        f = BaseCategoryForm({'name': 'Entertainment',
                              'slug': 'entertainment',
                              'url': 'entertainment'})
        self.assertTrue(f.is_valid())
        self.assertEqual(f.cleaned_data['name'], 'Entertainment')
        self.assertEqual(f.cleaned_data['slug'], 'entertainment')
        self.assertEqual(f.cleaned_data['url'], 'entertainment')
        c1 = f.save()
        # Testing whether the same object is returned from the
        # ORM... not the fastest way...

        self.assertEqual(Category.objects.count(), 1)
        self.assertEqual(c1, Category.objects.all()[0])
        self.assertEqual(c1.name, "Entertainment")

    def test_save_commit_false(self):
        # If you call save() with commit=False, then it will return an object that
        # hasn't yet been saved to the database. In this case, it's up to you to call
        # save() on the resulting model instance.
        f = BaseCategoryForm({'name': 'Third test', 'slug': 'third-test', 'url': 'third'})
        self.assertTrue(f.is_valid())
        c1 = f.save(commit=False)
        self.assertEqual(c1.name, "Third test")
        self.assertEqual(Category.objects.count(), 0)
        c1.save()
        self.assertEqual(Category.objects.count(), 1)

    def test_save_with_data_errors(self):
        # If you call save() with invalid data, you'll get a ValueError.
        f = BaseCategoryForm({'name': '', 'slug': 'not a slug!', 'url': 'foo'})
        self.assertEqual(f.errors['name'], ['This field is required.'])
        self.assertEqual(
            f.errors['slug'],
            ["Enter a valid 'slug' consisting of letters, numbers, underscores or hyphens."]
        )
        self.assertEqual(f.cleaned_data, {'url': 'foo'})
        msg = "The Category could not be created because the data didn't validate."
        with self.assertRaisesMessage(ValueError, msg):
            f.save()
        f = BaseCategoryForm({'name': '', 'slug': '', 'url': 'foo'})
        with self.assertRaisesMessage(ValueError, msg):
            f.save()

    def test_multi_fields(self):
        self.create_basic_data()
        self.maxDiff = None
        # ManyToManyFields are represented by a MultipleChoiceField, ForeignKeys and any
        # fields with the 'choices' attribute are represented by a ChoiceField.
        f = ArticleForm(auto_id=False)
        self.assertHTMLEqual(
            str(f),
            '''<tr><th>Headline:</th><td><input type="text" name="headline" maxlength="50" required></td></tr>
<tr><th>Slug:</th><td><input type="text" name="slug" maxlength="50" required></td></tr>
<tr><th>Pub date:</th><td><input type="text" name="pub_date" required></td></tr>
<tr><th>Writer:</th><td><select name="writer" required>
<option value="" selected>---------</option>
<option value="%s">Bob Woodward</option>
<option value="%s">Mike Royko</option>
</select></td></tr>
<tr><th>Article:</th><td><textarea rows="10" cols="40" name="article" required></textarea></td></tr>
<tr><th>Categories:</th><td><select multiple name="categories">
<option value="%s">Entertainment</option>
<option value="%s">It&#39;s a test</option>
<option value="%s">Third test</option>
</select></td></tr>
<tr><th>Status:</th><td><select name="status">
<option value="" selected>---------</option>
<option value="1">Draft</option>
<option value="2">Pending</option>
<option value="3">Live</option>
</select></td></tr>''' % (self.w_woodward.pk, self.w_royko.pk, self.c1.pk, self.c2.pk, self.c3.pk))

        # Add some categories and test the many-to-many form output.
        new_art = Article.objects.create(
            article="Hello.", headline="New headline", slug="new-headline",
            pub_date=datetime.date(1988, 1, 4), writer=self.w_royko)
        new_art.categories.add(Category.objects.get(name='Entertainment'))
        self.assertQuerysetEqual(new_art.categories.all(), ["Entertainment"])
        f = ArticleForm(auto_id=False, instance=new_art)
        self.assertHTMLEqual(
            f.as_ul(),
            '''<li>Headline: <input type="text" name="headline" value="New headline" maxlength="50" required></li>
<li>Slug: <input type="text" name="slug" value="new-headline" maxlength="50" required></li>
<li>Pub date: <input type="text" name="pub_date" value="1988-01-04" required></li>
<li>Writer: <select name="writer" required>
<option value="">---------</option>
<option value="%s">Bob Woodward</option>
<option value="%s" selected>Mike Royko</option>
</select></li>
<li>Article: <textarea rows="10" cols="40" name="article" required>Hello.</textarea></li>
<li>Categories: <select multiple name="categories">
<option value="%s" selected>Entertainment</option>
<option value="%s">It&#39;s a test</option>
<option value="%s">Third test</option>
</select></li>
<li>Status: <select name="status">
<option value="" selected>---------</option>
<option value="1">Draft</option>
<option value="2">Pending</option>
<option value="3">Live</option>
</select></li>''' % (self.w_woodward.pk, self.w_royko.pk, self.c1.pk, self.c2.pk, self.c3.pk))

    def test_subset_fields(self):
        # You can restrict a form to a subset of the complete list of fields
        # by providing a 'fields' argument. If you try to save a
        # model created with such a form, you need to ensure that the fields
        # that are _not_ on the form have default values, or are allowed to have
        # a value of None. If a field isn't specified on a form, the object created
        # from the form can't provide a value for that field!
        class PartialArticleForm(forms.ModelForm):
            class Meta:
                model = Article
                fields = ('headline', 'pub_date')

        f = PartialArticleForm(auto_id=False)
        self.assertHTMLEqual(
            str(f),
            '''<tr><th>Headline:</th><td><input type="text" name="headline" maxlength="50" required></td></tr>
<tr><th>Pub date:</th><td><input type="text" name="pub_date" required></td></tr>''')

        class PartialArticleFormWithSlug(forms.ModelForm):
            class Meta:
                model = Article
                fields = ('headline', 'slug', 'pub_date')

        w_royko = Writer.objects.create(name='Mike Royko')
        art = Article.objects.create(
            article="Hello.", headline="New headline", slug="new-headline",
            pub_date=datetime.date(1988, 1, 4), writer=w_royko)
        f = PartialArticleFormWithSlug({
            'headline': 'New headline',
            'slug': 'new-headline',
            'pub_date': '1988-01-04'
        }, auto_id=False, instance=art)
        self.assertHTMLEqual(
            f.as_ul(),
            '''<li>Headline: <input type="text" name="headline" value="New headline" maxlength="50" required></li>
<li>Slug: <input type="text" name="slug" value="new-headline" maxlength="50" required></li>
<li>Pub date: <input type="text" name="pub_date" value="1988-01-04" required></li>'''
        )
        self.assertTrue(f.is_valid())
        new_art = f.save()
        self.assertEqual(new_art.id, art.id)
        new_art = Article.objects.get(id=art.id)
        self.assertEqual(new_art.headline, 'New headline')

    def test_m2m_editing(self):
        self.create_basic_data()
        form_data = {
            'headline': 'New headline',
            'slug': 'new-headline',
            'pub_date': '1988-01-04',
            'writer': str(self.w_royko.pk),
            'article': 'Hello.',
            'categories': [str(self.c1.id), str(self.c2.id)]
        }
        # Create a new article, with categories, via the form.
        f = ArticleForm(form_data)
        new_art = f.save()
        new_art = Article.objects.get(id=new_art.id)
        art_id_1 = new_art.id
        self.assertQuerysetEqual(new_art.categories.order_by('name'), ["Entertainment", "It's a test"])

        # Now, submit form data with no categories. This deletes the existing categories.
        form_data['categories'] = []
        f = ArticleForm(form_data, instance=new_art)
        new_art = f.save()
        self.assertEqual(new_art.id, art_id_1)
        new_art = Article.objects.get(id=art_id_1)
        self.assertQuerysetEqual(new_art.categories.all(), [])

        # Create a new article, with no categories, via the form.
        f = ArticleForm(form_data)
        new_art = f.save()
        art_id_2 = new_art.id
        self.assertNotIn(art_id_2, (None, art_id_1))
        new_art = Article.objects.get(id=art_id_2)
        self.assertQuerysetEqual(new_art.categories.all(), [])

        # Create a new article, with categories, via the form, but use commit=False.
        # The m2m data won't be saved until save_m2m() is invoked on the form.
        form_data['categories'] = [str(self.c1.id), str(self.c2.id)]
        f = ArticleForm(form_data)
        new_art = f.save(commit=False)

        # Manually save the instance
        new_art.save()
        art_id_3 = new_art.id
        self.assertNotIn(art_id_3, (None, art_id_1, art_id_2))

        # The instance doesn't have m2m data yet
        new_art = Article.objects.get(id=art_id_3)
        self.assertQuerysetEqual(new_art.categories.all(), [])

        # Save the m2m data on the form
        f.save_m2m()
        self.assertQuerysetEqual(new_art.categories.order_by('name'), ["Entertainment", "It's a test"])

    def test_custom_form_fields(self):
        # Here, we define a custom ModelForm. Because it happens to have the same fields as
        # the Category model, we can just call the form's save() to apply its changes to an
        # existing Category instance.
        class ShortCategory(forms.ModelForm):
            name = forms.CharField(max_length=5)
            slug = forms.CharField(max_length=5)
            url = forms.CharField(max_length=3)

            class Meta:
                model = Category
                fields = '__all__'

        cat = Category.objects.create(name='Third test')
        form = ShortCategory({'name': 'Third', 'slug': 'third', 'url': '3rd'}, instance=cat)
        self.assertEqual(form.save().name, 'Third')
        self.assertEqual(Category.objects.get(id=cat.id).name, 'Third')

    def test_runtime_choicefield_populated(self):
        self.maxDiff = None
        # Here, we demonstrate that choices for a ForeignKey ChoiceField are determined
        # at runtime, based on the data in the database when the form is displayed, not
        # the data in the database when the form is instantiated.
        self.create_basic_data()
        f = ArticleForm(auto_id=False)
        self.assertHTMLEqual(
            f.as_ul(),
            '''<li>Headline: <input type="text" name="headline" maxlength="50" required></li>
<li>Slug: <input type="text" name="slug" maxlength="50" required></li>
<li>Pub date: <input type="text" name="pub_date" required></li>
<li>Writer: <select name="writer" required>
<option value="" selected>---------</option>
<option value="%s">Bob Woodward</option>
<option value="%s">Mike Royko</option>
</select></li>
<li>Article: <textarea rows="10" cols="40" name="article" required></textarea></li>
<li>Categories: <select multiple name="categories">
<option value="%s">Entertainment</option>
<option value="%s">It&#39;s a test</option>
<option value="%s">Third test</option>
</select> </li>
<li>Status: <select name="status">
<option value="" selected>---------</option>
<option value="1">Draft</option>
<option value="2">Pending</option>
<option value="3">Live</option>
</select></li>''' % (self.w_woodward.pk, self.w_royko.pk, self.c1.pk, self.c2.pk, self.c3.pk))

        c4 = Category.objects.create(name='Fourth', url='4th')
        w_bernstein = Writer.objects.create(name='Carl Bernstein')
        self.assertHTMLEqual(
            f.as_ul(),
            '''<li>Headline: <input type="text" name="headline" maxlength="50" required></li>
<li>Slug: <input type="text" name="slug" maxlength="50" required></li>
<li>Pub date: <input type="text" name="pub_date" required></li>
<li>Writer: <select name="writer" required>
<option value="" selected>---------</option>
<option value="%s">Bob Woodward</option>
<option value="%s">Carl Bernstein</option>
<option value="%s">Mike Royko</option>
</select></li>
<li>Article: <textarea rows="10" cols="40" name="article" required></textarea></li>
<li>Categories: <select multiple name="categories">
<option value="%s">Entertainment</option>
<option value="%s">It&#39;s a test</option>
<option value="%s">Third test</option>
<option value="%s">Fourth</option>
</select></li>
<li>Status: <select name="status">
<option value="" selected>---------</option>
<option value="1">Draft</option>
<option value="2">Pending</option>
<option value="3">Live</option>
</select></li>''' % (self.w_woodward.pk, w_bernstein.pk, self.w_royko.pk, self.c1.pk, self.c2.pk, self.c3.pk, c4.pk))

    def test_recleaning_model_form_instance(self):
        """
        Re-cleaning an instance that was added via a ModelForm shouldn't raise
        a pk uniqueness error.
        """
        class AuthorForm(forms.ModelForm):
            class Meta:
                model = Author
                fields = '__all__'

        form = AuthorForm({'full_name': 'Bob'})
        self.assertTrue(form.is_valid())
        obj = form.save()
        obj.name = 'Alice'
        obj.full_clean()


class ModelMultipleChoiceFieldTests(TestCase):
    def setUp(self):
        self.c1 = Category.objects.create(name='Entertainment', slug='entertainment', url='entertainment')
        self.c2 = Category.objects.create(name="It's a test", slug='its-test', url='test')
        self.c3 = Category.objects.create(name='Third', slug='third-test', url='third')

    def test_model_multiple_choice_field(self):
        f = forms.ModelMultipleChoiceField(Category.objects.all())
        self.assertEqual(list(f.choices), [
            (self.c1.pk, 'Entertainment'),
            (self.c2.pk, "It's a test"),
            (self.c3.pk, 'Third')])
        with self.assertRaises(ValidationError):
            f.clean(None)
        with self.assertRaises(ValidationError):
            f.clean([])
        self.assertQuerysetEqual(f.clean([self.c1.id]), ["Entertainment"])
        self.assertQuerysetEqual(f.clean([self.c2.id]), ["It's a test"])
        self.assertQuerysetEqual(f.clean([str(self.c1.id)]), ["Entertainment"])
        self.assertQuerysetEqual(
            f.clean([str(self.c1.id), str(self.c2.id)]),
            ["Entertainment", "It's a test"], ordered=False
        )
        self.assertQuerysetEqual(
            f.clean([self.c1.id, str(self.c2.id)]),
            ["Entertainment", "It's a test"], ordered=False
        )
        self.assertQuerysetEqual(
            f.clean((self.c1.id, str(self.c2.id))),
            ["Entertainment", "It's a test"], ordered=False
        )
        with self.assertRaises(ValidationError):
            f.clean(['100'])
        with self.assertRaises(ValidationError):
            f.clean('hello')
        with self.assertRaises(ValidationError):
            f.clean(['fail'])

        # Invalid types that require TypeError to be caught (#22808).
        with self.assertRaises(ValidationError):
            f.clean([['fail']])
        with self.assertRaises(ValidationError):
            f.clean([{'foo': 'bar'}])

        # Add a Category object *after* the ModelMultipleChoiceField has already been
        # instantiated. This proves clean() checks the database during clean() rather
        # than caching it at time of instantiation.
        # Note, we are using an id of 1006 here since tests that run before
        # this may create categories with primary keys up to 6. Use
        # a number that will not conflict.
        c6 = Category.objects.create(id=1006, name='Sixth', url='6th')
        self.assertQuerysetEqual(f.clean([c6.id]), ["Sixth"])

        # Delete a Category object *after* the ModelMultipleChoiceField has already been
        # instantiated. This proves clean() checks the database during clean() rather
        # than caching it at time of instantiation.
        Category.objects.get(url='6th').delete()
        with self.assertRaises(ValidationError):
            f.clean([c6.id])

    def test_model_multiple_choice_required_false(self):
        f = forms.ModelMultipleChoiceField(Category.objects.all(), required=False)
        self.assertIsInstance(f.clean([]), EmptyQuerySet)
        self.assertIsInstance(f.clean(()), EmptyQuerySet)
        with self.assertRaises(ValidationError):
            f.clean(['0'])
        with self.assertRaises(ValidationError):
            f.clean([str(self.c3.id), '0'])
        with self.assertRaises(ValidationError):
            f.clean([str(self.c1.id), '0'])

        # queryset can be changed after the field is created.
        f.queryset = Category.objects.exclude(name='Third')
        self.assertEqual(list(f.choices), [
            (self.c1.pk, 'Entertainment'),
            (self.c2.pk, "It's a test")])
        self.assertQuerysetEqual(f.clean([self.c2.id]), ["It's a test"])
        with self.assertRaises(ValidationError):
            f.clean([self.c3.id])
        with self.assertRaises(ValidationError):
            f.clean([str(self.c2.id), str(self.c3.id)])

        f.queryset = Category.objects.all()
        f.label_from_instance = lambda obj: "multicategory " + str(obj)
        self.assertEqual(list(f.choices), [
            (self.c1.pk, 'multicategory Entertainment'),
            (self.c2.pk, "multicategory It's a test"),
            (self.c3.pk, 'multicategory Third')])

    def test_model_multiple_choice_number_of_queries(self):
        """
        ModelMultipleChoiceField does O(1) queries instead of O(n) (#10156).
        """
        persons = [Writer.objects.create(name="Person %s" % i) for i in range(30)]

        f = forms.ModelMultipleChoiceField(queryset=Writer.objects.all())
        self.assertNumQueries(1, f.clean, [p.pk for p in persons[1:11:2]])

    def test_model_multiple_choice_run_validators(self):
        """
        ModelMultipleChoiceField run given validators (#14144).
        """
        for i in range(30):
            Writer.objects.create(name="Person %s" % i)

        self._validator_run = False

        def my_validator(value):
            self._validator_run = True

        f = forms.ModelMultipleChoiceField(queryset=Writer.objects.all(), validators=[my_validator])
        f.clean([p.pk for p in Writer.objects.all()[8:9]])
        self.assertTrue(self._validator_run)

    def test_model_multiple_choice_show_hidden_initial(self):
        """
        Test support of show_hidden_initial by ModelMultipleChoiceField.
        """
        class WriterForm(forms.Form):
            persons = forms.ModelMultipleChoiceField(show_hidden_initial=True, queryset=Writer.objects.all())

        person1 = Writer.objects.create(name="Person 1")
        person2 = Writer.objects.create(name="Person 2")

        form = WriterForm(initial={'persons': [person1, person2]},
                          data={'initial-persons': [str(person1.pk), str(person2.pk)],
                                'persons': [str(person1.pk), str(person2.pk)]})
        self.assertTrue(form.is_valid())
        self.assertFalse(form.has_changed())

        form = WriterForm(initial={'persons': [person1, person2]},
                          data={'initial-persons': [str(person1.pk), str(person2.pk)],
                                'persons': [str(person2.pk)]})
        self.assertTrue(form.is_valid())
        self.assertTrue(form.has_changed())

    def test_model_multiple_choice_field_22745(self):
        """
        #22745 -- Make sure that ModelMultipleChoiceField with
        CheckboxSelectMultiple widget doesn't produce unnecessary db queries
        when accessing its BoundField's attrs.
        """
        class ModelMultipleChoiceForm(forms.Form):
            categories = forms.ModelMultipleChoiceField(Category.objects.all(), widget=forms.CheckboxSelectMultiple)

        form = ModelMultipleChoiceForm()
        field = form['categories']  # BoundField
        template = Template('{{ field.name }}{{ field }}{{ field.help_text }}')
        with self.assertNumQueries(1):
            template.render(Context({'field': field}))

    def test_show_hidden_initial_changed_queries_efficiently(self):
        class WriterForm(forms.Form):
            persons = forms.ModelMultipleChoiceField(
                show_hidden_initial=True, queryset=Writer.objects.all())

        writers = (Writer.objects.create(name=str(x)) for x in range(0, 50))
        writer_pks = tuple(x.pk for x in writers)
        form = WriterForm(data={'initial-persons': writer_pks})
        with self.assertNumQueries(1):
            self.assertTrue(form.has_changed())

    def test_clean_does_deduplicate_values(self):
        class WriterForm(forms.Form):
            persons = forms.ModelMultipleChoiceField(queryset=Writer.objects.all())

        person1 = Writer.objects.create(name="Person 1")
        form = WriterForm(data={})
        queryset = form.fields['persons'].clean([str(person1.pk)] * 50)
        sql, params = queryset.query.sql_with_params()
        self.assertEqual(len(params), 1)

    def test_to_field_name_with_initial_data(self):
        class ArticleCategoriesForm(forms.ModelForm):
            categories = forms.ModelMultipleChoiceField(Category.objects.all(), to_field_name='slug')

            class Meta:
                model = Article
                fields = ['categories']

        article = Article.objects.create(
            headline='Test article',
            slug='test-article',
            pub_date=datetime.date(1988, 1, 4),
            writer=Writer.objects.create(name='Test writer'),
            article='Hello.',
        )
        article.categories.add(self.c2, self.c3)
        form = ArticleCategoriesForm(instance=article)
        self.assertCountEqual(form['categories'].value(), [self.c2.slug, self.c3.slug])


class ModelOneToOneFieldTests(TestCase):
    def test_modelform_onetoonefield(self):
        class ImprovedArticleForm(forms.ModelForm):
            class Meta:
                model = ImprovedArticle
                fields = '__all__'

        class ImprovedArticleWithParentLinkForm(forms.ModelForm):
            class Meta:
                model = ImprovedArticleWithParentLink
                fields = '__all__'

        self.assertEqual(list(ImprovedArticleForm.base_fields), ['article'])
        self.assertEqual(list(ImprovedArticleWithParentLinkForm.base_fields), [])

    def test_modelform_subclassed_model(self):
        class BetterWriterForm(forms.ModelForm):
            class Meta:
                # BetterWriter model is a subclass of Writer with an additional `score` field
                model = BetterWriter
                fields = '__all__'

        bw = BetterWriter.objects.create(name='Joe Better', score=10)
        self.assertEqual(sorted(model_to_dict(bw)), ['id', 'name', 'score', 'writer_ptr'])

        form = BetterWriterForm({'name': 'Some Name', 'score': 12})
        self.assertTrue(form.is_valid())
        bw2 = form.save()
        self.assertEqual(bw2.score, 12)

    def test_onetoonefield(self):
        class WriterProfileForm(forms.ModelForm):
            class Meta:
                # WriterProfile has a OneToOneField to Writer
                model = WriterProfile
                fields = '__all__'

        self.w_royko = Writer.objects.create(name='Mike Royko')
        self.w_woodward = Writer.objects.create(name='Bob Woodward')

        form = WriterProfileForm()
        self.assertHTMLEqual(
            form.as_p(),
            '''<p><label for="id_writer">Writer:</label> <select name="writer" id="id_writer" required>
<option value="" selected>---------</option>
<option value="%s">Bob Woodward</option>
<option value="%s">Mike Royko</option>
</select></p>
<p><label for="id_age">Age:</label> <input type="number" name="age" id="id_age" min="0" required></p>''' % (
                self.w_woodward.pk, self.w_royko.pk,
            )
        )

        data = {
            'writer': str(self.w_woodward.pk),
            'age': '65',
        }
        form = WriterProfileForm(data)
        instance = form.save()
        self.assertEqual(str(instance), 'Bob Woodward is 65')

        form = WriterProfileForm(instance=instance)
        self.assertHTMLEqual(
            form.as_p(),
            '''<p><label for="id_writer">Writer:</label> <select name="writer" id="id_writer" required>
<option value="">---------</option>
<option value="%s" selected>Bob Woodward</option>
<option value="%s">Mike Royko</option>
</select></p>
<p><label for="id_age">Age:</label>
<input type="number" name="age" value="65" id="id_age" min="0" required></p>''' % (
                self.w_woodward.pk, self.w_royko.pk,
            )
        )

    def test_assignment_of_none(self):
        class AuthorForm(forms.ModelForm):
            class Meta:
                model = Author
                fields = ['publication', 'full_name']

        publication = Publication.objects.create(title="Pravda", date_published=datetime.date(1991, 8, 22))
        author = Author.objects.create(publication=publication, full_name='John Doe')
        form = AuthorForm({'publication': '', 'full_name': 'John Doe'}, instance=author)
        self.assertTrue(form.is_valid())
        self.assertIsNone(form.cleaned_data['publication'])
        author = form.save()
        # author object returned from form still retains original publication object
        # that's why we need to retrieve it from database again
        new_author = Author.objects.get(pk=author.pk)
        self.assertIsNone(new_author.publication)

    def test_assignment_of_none_null_false(self):
        class AuthorForm(forms.ModelForm):
            class Meta:
                model = Author1
                fields = ['publication', 'full_name']

        publication = Publication.objects.create(title="Pravda", date_published=datetime.date(1991, 8, 22))
        author = Author1.objects.create(publication=publication, full_name='John Doe')
        form = AuthorForm({'publication': '', 'full_name': 'John Doe'}, instance=author)
        self.assertFalse(form.is_valid())


class FileAndImageFieldTests(TestCase):
    def test_clean_false(self):
        """
        If the ``clean`` method on a non-required FileField receives False as
        the data (meaning clear the field value), it returns False, regardless
        of the value of ``initial``.
        """
        f = forms.FileField(required=False)
        self.assertIs(f.clean(False), False)
        self.assertIs(f.clean(False, 'initial'), False)

    def test_clean_false_required(self):
        """
        If the ``clean`` method on a required FileField receives False as the
        data, it has the same effect as None: initial is returned if non-empty,
        otherwise the validation catches the lack of a required value.
        """
        f = forms.FileField(required=True)
        self.assertEqual(f.clean(False, 'initial'), 'initial')
        with self.assertRaises(ValidationError):
            f.clean(False)

    def test_full_clear(self):
        """
        Integration happy-path test that a model FileField can actually be set
        and cleared via a ModelForm.
        """
        class DocumentForm(forms.ModelForm):
            class Meta:
                model = Document
                fields = '__all__'

        form = DocumentForm()
        self.assertIn('name="myfile"', str(form))
        self.assertNotIn('myfile-clear', str(form))
        form = DocumentForm(files={'myfile': SimpleUploadedFile('something.txt', b'content')})
        self.assertTrue(form.is_valid())
        doc = form.save(commit=False)
        self.assertEqual(doc.myfile.name, 'something.txt')
        form = DocumentForm(instance=doc)
        self.assertIn('myfile-clear', str(form))
        form = DocumentForm(instance=doc, data={'myfile-clear': 'true'})
        doc = form.save(commit=False)
        self.assertFalse(doc.myfile)

    def test_clear_and_file_contradiction(self):
        """
        If the user submits a new file upload AND checks the clear checkbox,
        they get a validation error, and the bound redisplay of the form still
        includes the current file and the clear checkbox.
        """
        class DocumentForm(forms.ModelForm):
            class Meta:
                model = Document
                fields = '__all__'

        form = DocumentForm(files={'myfile': SimpleUploadedFile('something.txt', b'content')})
        self.assertTrue(form.is_valid())
        doc = form.save(commit=False)
        form = DocumentForm(
            instance=doc,
            files={'myfile': SimpleUploadedFile('something.txt', b'content')},
            data={'myfile-clear': 'true'},
        )
        self.assertTrue(not form.is_valid())
        self.assertEqual(form.errors['myfile'],
                         ['Please either submit a file or check the clear checkbox, not both.'])
        rendered = str(form)
        self.assertIn('something.txt', rendered)
        self.assertIn('myfile-clear', rendered)

    def test_render_empty_file_field(self):
        class DocumentForm(forms.ModelForm):
            class Meta:
                model = Document
                fields = '__all__'

        doc = Document.objects.create()
        form = DocumentForm(instance=doc)
        self.assertHTMLEqual(
            str(form['myfile']),
            '<input id="id_myfile" name="myfile" type="file">'
        )

    def test_file_field_data(self):
        # Test conditions when files is either not given or empty.
        f = TextFileForm(data={'description': 'Assistance'})
        self.assertFalse(f.is_valid())
        f = TextFileForm(data={'description': 'Assistance'}, files={})
        self.assertFalse(f.is_valid())

        # Upload a file and ensure it all works as expected.
        f = TextFileForm(
            data={'description': 'Assistance'},
            files={'file': SimpleUploadedFile('test1.txt', b'hello world')},
        )
        self.assertTrue(f.is_valid())
        self.assertEqual(type(f.cleaned_data['file']), SimpleUploadedFile)
        instance = f.save()
        self.assertEqual(instance.file.name, 'tests/test1.txt')
        instance.file.delete()

        # If the previous file has been deleted, the file name can be reused
        f = TextFileForm(
            data={'description': 'Assistance'},
            files={'file': SimpleUploadedFile('test1.txt', b'hello world')},
        )
        self.assertTrue(f.is_valid())
        self.assertEqual(type(f.cleaned_data['file']), SimpleUploadedFile)
        instance = f.save()
        self.assertEqual(instance.file.name, 'tests/test1.txt')

        # Check if the max_length attribute has been inherited from the model.
        f = TextFileForm(
            data={'description': 'Assistance'},
            files={'file': SimpleUploadedFile('test-maxlength.txt', b'hello world')},
        )
        self.assertFalse(f.is_valid())

        # Edit an instance that already has the file defined in the model. This will not
        # save the file again, but leave it exactly as it is.
        f = TextFileForm({'description': 'Assistance'}, instance=instance)
        self.assertTrue(f.is_valid())
        self.assertEqual(f.cleaned_data['file'].name, 'tests/test1.txt')
        instance = f.save()
        self.assertEqual(instance.file.name, 'tests/test1.txt')

        # Delete the current file since this is not done by Django.
        instance.file.delete()

        # Override the file by uploading a new one.
        f = TextFileForm(
            data={'description': 'Assistance'},
            files={'file': SimpleUploadedFile('test2.txt', b'hello world')},
            instance=instance,
        )
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.file.name, 'tests/test2.txt')

        # Delete the current file since this is not done by Django.
        instance.file.delete()
        instance.delete()

    def test_filefield_required_false(self):
        # Test the non-required FileField
        f = TextFileForm(data={'description': 'Assistance'})
        f.fields['file'].required = False
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.file.name, '')

        f = TextFileForm(
            data={'description': 'Assistance'},
            files={'file': SimpleUploadedFile('test3.txt', b'hello world')},
            instance=instance,
        )
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.file.name, 'tests/test3.txt')

        # Instance can be edited w/out re-uploading the file and existing file should be preserved.
        f = TextFileForm({'description': 'New Description'}, instance=instance)
        f.fields['file'].required = False
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.description, 'New Description')
        self.assertEqual(instance.file.name, 'tests/test3.txt')

        # Delete the current file since this is not done by Django.
        instance.file.delete()
        instance.delete()

    def test_custom_file_field_save(self):
        """
        Regression for #11149: save_form_data should be called only once
        """
        class CFFForm(forms.ModelForm):
            class Meta:
                model = CustomFF
                fields = '__all__'

        # It's enough that the form saves without error -- the custom save routine will
        # generate an AssertionError if it is called more than once during save.
        form = CFFForm(data={'f': None})
        form.save()

    def test_file_field_multiple_save(self):
        """
        Simulate a file upload and check how many times Model.save() gets
        called. Test for bug #639.
        """
        class PhotoForm(forms.ModelForm):
            class Meta:
                model = Photo
                fields = '__all__'

        # Grab an image for testing.
        filename = os.path.join(os.path.dirname(__file__), 'test.png')
        with open(filename, "rb") as fp:
            img = fp.read()

        # Fake a POST QueryDict and FILES MultiValueDict.
        data = {'title': 'Testing'}
        files = {"image": SimpleUploadedFile('test.png', img, 'image/png')}

        form = PhotoForm(data=data, files=files)
        p = form.save()

        try:
            # Check the savecount stored on the object (see the model).
            self.assertEqual(p._savecount, 1)
        finally:
            # Delete the "uploaded" file to avoid clogging /tmp.
            p = Photo.objects.get()
            p.image.delete(save=False)

    def test_file_path_field_blank(self):
        """FilePathField(blank=True) includes the empty option."""
        class FPForm(forms.ModelForm):
            class Meta:
                model = FilePathModel
                fields = '__all__'

        form = FPForm()
        self.assertEqual([name for _, name in form['path'].field.choices], ['---------', 'models.py'])

    @skipUnless(test_images, "Pillow not installed")
    def test_image_field(self):
        # ImageField and FileField are nearly identical, but they differ slightly when
        # it comes to validation. This specifically tests that #6302 is fixed for
        # both file fields and image fields.

        with open(os.path.join(os.path.dirname(__file__), 'test.png'), 'rb') as fp:
            image_data = fp.read()
        with open(os.path.join(os.path.dirname(__file__), 'test2.png'), 'rb') as fp:
            image_data2 = fp.read()

        f = ImageFileForm(
            data={'description': 'An image'},
            files={'image': SimpleUploadedFile('test.png', image_data)},
        )
        self.assertTrue(f.is_valid())
        self.assertEqual(type(f.cleaned_data['image']), SimpleUploadedFile)
        instance = f.save()
        self.assertEqual(instance.image.name, 'tests/test.png')
        self.assertEqual(instance.width, 16)
        self.assertEqual(instance.height, 16)

        # Delete the current file since this is not done by Django, but don't save
        # because the dimension fields are not null=True.
        instance.image.delete(save=False)
        f = ImageFileForm(
            data={'description': 'An image'},
            files={'image': SimpleUploadedFile('test.png', image_data)},
        )
        self.assertTrue(f.is_valid())
        self.assertEqual(type(f.cleaned_data['image']), SimpleUploadedFile)
        instance = f.save()
        self.assertEqual(instance.image.name, 'tests/test.png')
        self.assertEqual(instance.width, 16)
        self.assertEqual(instance.height, 16)

        # Edit an instance that already has the (required) image defined in the model. This will not
        # save the image again, but leave it exactly as it is.

        f = ImageFileForm(data={'description': 'Look, it changed'}, instance=instance)
        self.assertTrue(f.is_valid())
        self.assertEqual(f.cleaned_data['image'].name, 'tests/test.png')
        instance = f.save()
        self.assertEqual(instance.image.name, 'tests/test.png')
        self.assertEqual(instance.height, 16)
        self.assertEqual(instance.width, 16)

        # Delete the current file since this is not done by Django, but don't save
        # because the dimension fields are not null=True.
        instance.image.delete(save=False)
        # Override the file by uploading a new one.

        f = ImageFileForm(
            data={'description': 'Changed it'},
            files={'image': SimpleUploadedFile('test2.png', image_data2)},
            instance=instance,
        )
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.image.name, 'tests/test2.png')
        self.assertEqual(instance.height, 32)
        self.assertEqual(instance.width, 48)

        # Delete the current file since this is not done by Django, but don't save
        # because the dimension fields are not null=True.
        instance.image.delete(save=False)
        instance.delete()

        f = ImageFileForm(
            data={'description': 'Changed it'},
            files={'image': SimpleUploadedFile('test2.png', image_data2)},
        )
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.image.name, 'tests/test2.png')
        self.assertEqual(instance.height, 32)
        self.assertEqual(instance.width, 48)

        # Delete the current file since this is not done by Django, but don't save
        # because the dimension fields are not null=True.
        instance.image.delete(save=False)
        instance.delete()

        # Test the non-required ImageField
        # Note: In Oracle, we expect a null ImageField to return '' instead of
        # None.
        if connection.features.interprets_empty_strings_as_nulls:
            expected_null_imagefield_repr = ''
        else:
            expected_null_imagefield_repr = None

        f = OptionalImageFileForm(data={'description': 'Test'})
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.image.name, expected_null_imagefield_repr)
        self.assertIsNone(instance.width)
        self.assertIsNone(instance.height)

        f = OptionalImageFileForm(
            data={'description': 'And a final one'},
            files={'image': SimpleUploadedFile('test3.png', image_data)},
            instance=instance,
        )
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.image.name, 'tests/test3.png')
        self.assertEqual(instance.width, 16)
        self.assertEqual(instance.height, 16)

        # Editing the instance without re-uploading the image should not affect
        # the image or its width/height properties.
        f = OptionalImageFileForm({'description': 'New Description'}, instance=instance)
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.description, 'New Description')
        self.assertEqual(instance.image.name, 'tests/test3.png')
        self.assertEqual(instance.width, 16)
        self.assertEqual(instance.height, 16)

        # Delete the current file since this is not done by Django.
        instance.image.delete()
        instance.delete()

        f = OptionalImageFileForm(
            data={'description': 'And a final one'},
            files={'image': SimpleUploadedFile('test4.png', image_data2)}
        )
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.image.name, 'tests/test4.png')
        self.assertEqual(instance.width, 48)
        self.assertEqual(instance.height, 32)
        instance.delete()
        # Test callable upload_to behavior that's dependent on the value of another field in the model
        f = ImageFileForm(
            data={'description': 'And a final one', 'path': 'foo'},
            files={'image': SimpleUploadedFile('test4.png', image_data)},
        )
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.image.name, 'foo/test4.png')
        instance.delete()

        # Editing an instance that has an image without an extension shouldn't
        # fail validation. First create:
        f = NoExtensionImageFileForm(
            data={'description': 'An image'},
            files={'image': SimpleUploadedFile('test.png', image_data)},
        )
        self.assertTrue(f.is_valid())
        instance = f.save()
        self.assertEqual(instance.image.name, 'tests/no_extension')
        # Then edit:
        f = NoExtensionImageFileForm(data={'description': 'Edited image'}, instance=instance)
        self.assertTrue(f.is_valid())


class ModelOtherFieldTests(SimpleTestCase):
    def test_big_integer_field(self):
        bif = BigIntForm({'biggie': '-9223372036854775808'})
        self.assertTrue(bif.is_valid())
        bif = BigIntForm({'biggie': '-9223372036854775809'})
        self.assertFalse(bif.is_valid())
        self.assertEqual(
            bif.errors,
            {'biggie': ['Ensure this value is greater than or equal to -9223372036854775808.']}
        )
        bif = BigIntForm({'biggie': '9223372036854775807'})
        self.assertTrue(bif.is_valid())
        bif = BigIntForm({'biggie': '9223372036854775808'})
        self.assertFalse(bif.is_valid())
        self.assertEqual(bif.errors, {'biggie': ['Ensure this value is less than or equal to 9223372036854775807.']})

    def test_url_on_modelform(self):
        "Check basic URL field validation on model forms"
        class HomepageForm(forms.ModelForm):
            class Meta:
                model = Homepage
                fields = '__all__'

        self.assertFalse(HomepageForm({'url': 'foo'}).is_valid())
        self.assertFalse(HomepageForm({'url': 'http://'}).is_valid())
        self.assertFalse(HomepageForm({'url': 'http://example'}).is_valid())
        self.assertFalse(HomepageForm({'url': 'http://example.'}).is_valid())
        self.assertFalse(HomepageForm({'url': 'http://com.'}).is_valid())

        self.assertTrue(HomepageForm({'url': 'http://localhost'}).is_valid())
        self.assertTrue(HomepageForm({'url': 'http://example.com'}).is_valid())
        self.assertTrue(HomepageForm({'url': 'http://www.example.com'}).is_valid())
        self.assertTrue(HomepageForm({'url': 'http://www.example.com:8000'}).is_valid())
        self.assertTrue(HomepageForm({'url': 'http://www.example.com/test'}).is_valid())
        self.assertTrue(HomepageForm({'url': 'http://www.example.com:8000/test'}).is_valid())
        self.assertTrue(HomepageForm({'url': 'http://example.com/foo/bar'}).is_valid())

    def test_modelform_non_editable_field(self):
        """
        When explicitly including a non-editable field in a ModelForm, the
        error message should be explicit.
        """
        # 'created', non-editable, is excluded by default
        self.assertNotIn('created', ArticleForm().fields)

        msg = "'created' cannot be specified for Article model form as it is a non-editable field"
        with self.assertRaisesMessage(FieldError, msg):
            class InvalidArticleForm(forms.ModelForm):
                class Meta:
                    model = Article
                    fields = ('headline', 'created')

    def test_http_prefixing(self):
        """
        If the http:// prefix is omitted on form input, the field adds it again. (Refs #13613)
        """
        class HomepageForm(forms.ModelForm):
            class Meta:
                model = Homepage
                fields = '__all__'

        form = HomepageForm({'url': 'example.com'})
        self.assertTrue(form.is_valid())
        self.assertEqual(form.cleaned_data['url'], 'http://example.com')

        form = HomepageForm({'url': 'example.com/test'})
        self.assertTrue(form.is_valid())
        self.assertEqual(form.cleaned_data['url'], 'http://example.com/test')


class OtherModelFormTests(TestCase):
    def test_media_on_modelform(self):
        # Similar to a regular Form class you can define custom media to be used on
        # the ModelForm.
        f = ModelFormWithMedia()
        self.assertHTMLEqual(
            str(f.media),
            '''<link href="/some/form/css" type="text/css" media="all" rel="stylesheet">
<script type="text/javascript" src="/some/form/javascript"></script>'''
        )

    def test_choices_type(self):
        # Choices on CharField and IntegerField
        f = ArticleForm()
        with self.assertRaises(ValidationError):
            f.fields['status'].clean('42')

        f = ArticleStatusForm()
        with self.assertRaises(ValidationError):
            f.fields['status'].clean('z')

    def test_prefetch_related_queryset(self):
        """
        ModelChoiceField should respect a prefetch_related() on its queryset.
        """
        blue = Colour.objects.create(name='blue')
        red = Colour.objects.create(name='red')
        multicolor_item = ColourfulItem.objects.create()
        multicolor_item.colours.add(blue, red)
        red_item = ColourfulItem.objects.create()
        red_item.colours.add(red)

        class ColorModelChoiceField(forms.ModelChoiceField):
            def label_from_instance(self, obj):
                return ', '.join(c.name for c in obj.colours.all())

        field = ColorModelChoiceField(ColourfulItem.objects.prefetch_related('colours'))
        with self.assertNumQueries(3):  # would be 4 if prefetch is ignored
            self.assertEqual(tuple(field.choices), (
                ('', '---------'),
                (multicolor_item.pk, 'blue, red'),
                (red_item.pk, 'red'),
            ))

    def test_foreignkeys_which_use_to_field(self):
        apple = Inventory.objects.create(barcode=86, name='Apple')
        Inventory.objects.create(barcode=22, name='Pear')
        core = Inventory.objects.create(barcode=87, name='Core', parent=apple)

        field = forms.ModelChoiceField(Inventory.objects.all(), to_field_name='barcode')
        self.assertEqual(tuple(field.choices), (
            ('', '---------'),
            (86, 'Apple'),
            (87, 'Core'),
            (22, 'Pear')))

        form = InventoryForm(instance=core)
        self.assertHTMLEqual(str(form['parent']), '''<select name="parent" id="id_parent">
<option value="">---------</option>
<option value="86" selected>Apple</option>
<option value="87">Core</option>
<option value="22">Pear</option>
</select>''')
        data = model_to_dict(core)
        data['parent'] = '22'
        form = InventoryForm(data=data, instance=core)
        core = form.save()
        self.assertEqual(core.parent.name, 'Pear')

        class CategoryForm(forms.ModelForm):
            description = forms.CharField()

            class Meta:
                model = Category
                fields = ['description', 'url']

        self.assertEqual(list(CategoryForm.base_fields), ['description', 'url'])

        self.assertHTMLEqual(
            str(CategoryForm()),
            '''<tr><th><label for="id_description">Description:</label></th>
<td><input type="text" name="description" id="id_description" required></td></tr>
<tr><th><label for="id_url">The URL:</label></th>
<td><input id="id_url" type="text" name="url" maxlength="40" required></td></tr>'''
        )
        # to_field_name should also work on ModelMultipleChoiceField ##################

        field = forms.ModelMultipleChoiceField(Inventory.objects.all(), to_field_name='barcode')
        self.assertEqual(tuple(field.choices), ((86, 'Apple'), (87, 'Core'), (22, 'Pear')))
        self.assertQuerysetEqual(field.clean([86]), ['Apple'])

        form = SelectInventoryForm({'items': [87, 22]})
        self.assertTrue(form.is_valid())
        self.assertEqual(len(form.cleaned_data), 1)
        self.assertQuerysetEqual(form.cleaned_data['items'], ['Core', 'Pear'])

    def test_model_field_that_returns_none_to_exclude_itself_with_explicit_fields(self):
        self.assertEqual(list(CustomFieldForExclusionForm.base_fields), ['name'])
        self.assertHTMLEqual(
            str(CustomFieldForExclusionForm()),
            '''<tr><th><label for="id_name">Name:</label></th>
<td><input id="id_name" type="text" name="name" maxlength="10" required></td></tr>'''
        )

    def test_iterable_model_m2m(self):
        class ColourfulItemForm(forms.ModelForm):
            class Meta:
                model = ColourfulItem
                fields = '__all__'

        colour = Colour.objects.create(name='Blue')
        form = ColourfulItemForm()
        self.maxDiff = 1024
        self.assertHTMLEqual(
            form.as_p(),
            """<p><label for="id_name">Name:</label> <input id="id_name" type="text" name="name" maxlength="50" required></p>
        <p><label for="id_colours">Colours:</label>
        <select multiple name="colours" id="id_colours" required>
        <option value="%(blue_pk)s">Blue</option>
        </select></p>"""
            % {'blue_pk': colour.pk})

    def test_callable_field_default(self):
        class PublicationDefaultsForm(forms.ModelForm):
            class Meta:
                model = PublicationDefaults
                fields = ('title', 'date_published', 'mode', 'category')

        self.maxDiff = 2000
        form = PublicationDefaultsForm()
        today_str = str(datetime.date.today())
        self.assertHTMLEqual(
            form.as_p(),
            """
            <p><label for="id_title">Title:</label>
                <input id="id_title" maxlength="30" name="title" type="text" required></p>
            <p><label for="id_date_published">Date published:</label>
                <input id="id_date_published" name="date_published" type="text" value="{0}" required>
                <input id="initial-id_date_published" name="initial-date_published" type="hidden" value="{0}"></p>
            <p><label for="id_mode">Mode:</label> <select id="id_mode" name="mode">
                <option value="di" selected>direct</option>
                <option value="de">delayed</option></select>
                <input id="initial-id_mode" name="initial-mode" type="hidden" value="di"></p>
           <p><label for="id_category">Category:</label> <select id="id_category" name="category">
                <option value="1">Games</option>
                <option value="2">Comics</option>
                <option value="3" selected>Novel</option></select>
                <input id="initial-id_category" name="initial-category" type="hidden" value="3">
            """.format(today_str)
        )
        empty_data = {
            'title': '',
            'date_published': today_str,
            'initial-date_published': today_str,
            'mode': 'di',
            'initial-mode': 'di',
            'category': '3',
            'initial-category': '3',
        }
        bound_form = PublicationDefaultsForm(empty_data)
        self.assertFalse(bound_form.has_changed())


class ModelFormCustomErrorTests(SimpleTestCase):
    def test_custom_error_messages(self):
        data = {'name1': '@#$!!**@#$', 'name2': '@#$!!**@#$'}
        errors = CustomErrorMessageForm(data).errors
        self.assertHTMLEqual(
            str(errors['name1']),
            '<ul class="errorlist"><li>Form custom error message.</li></ul>'
        )
        self.assertHTMLEqual(
            str(errors['name2']),
            '<ul class="errorlist"><li>Model custom error message.</li></ul>'
        )

    def test_model_clean_error_messages(self):
        data = {'name1': 'FORBIDDEN_VALUE', 'name2': 'ABC'}
        form = CustomErrorMessageForm(data)
        self.assertFalse(form.is_valid())
        self.assertHTMLEqual(
            str(form.errors['name1']),
            '<ul class="errorlist"><li>Model.clean() error messages.</li></ul>'
        )
        data = {'name1': 'FORBIDDEN_VALUE2', 'name2': 'ABC'}
        form = CustomErrorMessageForm(data)
        self.assertFalse(form.is_valid())
        self.assertHTMLEqual(
            str(form.errors['name1']),
            '<ul class="errorlist"><li>Model.clean() error messages (simpler syntax).</li></ul>'
        )
        data = {'name1': 'GLOBAL_ERROR', 'name2': 'ABC'}
        form = CustomErrorMessageForm(data)
        self.assertFalse(form.is_valid())
        self.assertEqual(form.errors['__all__'], ['Global error message.'])


class CustomCleanTests(TestCase):
    def test_override_clean(self):
        """
        Regression for #12596: Calling super from ModelForm.clean() should be
        optional.
        """
        class TripleFormWithCleanOverride(forms.ModelForm):
            class Meta:
                model = Triple
                fields = '__all__'

            def clean(self):
                if not self.cleaned_data['left'] == self.cleaned_data['right']:
                    raise forms.ValidationError('Left and right should be equal')
                return self.cleaned_data

        form = TripleFormWithCleanOverride({'left': 1, 'middle': 2, 'right': 1})
        self.assertTrue(form.is_valid())
        # form.instance.left will be None if the instance was not constructed
        # by form.full_clean().
        self.assertEqual(form.instance.left, 1)

    def test_model_form_clean_applies_to_model(self):
        """
        Regression test for #12960. Make sure the cleaned_data returned from
        ModelForm.clean() is applied to the model instance.
        """
        class CategoryForm(forms.ModelForm):
            class Meta:
                model = Category
                fields = '__all__'

            def clean(self):
                self.cleaned_data['name'] = self.cleaned_data['name'].upper()
                return self.cleaned_data

        data = {'name': 'Test', 'slug': 'test', 'url': '/test'}
        form = CategoryForm(data)
        category = form.save()
        self.assertEqual(category.name, 'TEST')


class ModelFormInheritanceTests(SimpleTestCase):
    def test_form_subclass_inheritance(self):
        class Form(forms.Form):
            age = forms.IntegerField()

        class ModelForm(forms.ModelForm, Form):
            class Meta:
                model = Writer
                fields = '__all__'

        self.assertEqual(list(ModelForm().fields), ['name', 'age'])

    def test_field_removal(self):
        class ModelForm(forms.ModelForm):
            class Meta:
                model = Writer
                fields = '__all__'

        class Mixin:
            age = None

        class Form(forms.Form):
            age = forms.IntegerField()

        class Form2(forms.Form):
            foo = forms.IntegerField()

        self.assertEqual(list(ModelForm().fields), ['name'])
        self.assertEqual(list(type('NewForm', (Mixin, Form), {})().fields), [])
        self.assertEqual(list(type('NewForm', (Form2, Mixin, Form), {})().fields), ['foo'])
        self.assertEqual(list(type('NewForm', (Mixin, ModelForm, Form), {})().fields), ['name'])
        self.assertEqual(list(type('NewForm', (ModelForm, Mixin, Form), {})().fields), ['name'])
        self.assertEqual(list(type('NewForm', (ModelForm, Form, Mixin), {})().fields), ['name', 'age'])
        self.assertEqual(list(type('NewForm', (ModelForm, Form), {'age': None})().fields), ['name'])

    def test_field_removal_name_clashes(self):
        """
        Form fields can be removed in subclasses by setting them to None
        (#22510).
        """
        class MyForm(forms.ModelForm):
            media = forms.CharField()

            class Meta:
                model = Writer
                fields = '__all__'

        class SubForm(MyForm):
            media = None

        self.assertIn('media', MyForm().fields)
        self.assertNotIn('media', SubForm().fields)
        self.assertTrue(hasattr(MyForm, 'media'))
        self.assertTrue(hasattr(SubForm, 'media'))


class StumpJokeForm(forms.ModelForm):
    class Meta:
        model = StumpJoke
        fields = '__all__'


class CustomFieldWithQuerysetButNoLimitChoicesTo(forms.Field):
    queryset = 42


class StumpJokeWithCustomFieldForm(forms.ModelForm):
    custom = CustomFieldWithQuerysetButNoLimitChoicesTo()

    class Meta:
        model = StumpJoke
        fields = ()


class LimitChoicesToTests(TestCase):
    """
    Tests the functionality of ``limit_choices_to``.
    """
    @classmethod
    def setUpTestData(cls):
        cls.threepwood = Character.objects.create(
            username='threepwood',
            last_action=datetime.datetime.today() + datetime.timedelta(days=1),
        )
        cls.marley = Character.objects.create(
            username='marley',
            last_action=datetime.datetime.today() - datetime.timedelta(days=1),
        )

    def test_limit_choices_to_callable_for_fk_rel(self):
        """
        A ForeignKey can use limit_choices_to as a callable (#2554).
        """
        stumpjokeform = StumpJokeForm()
        self.assertSequenceEqual(stumpjokeform.fields['most_recently_fooled'].queryset, [self.threepwood])

    def test_limit_choices_to_callable_for_m2m_rel(self):
        """
        A ManyToManyField can use limit_choices_to as a callable (#2554).
        """
        stumpjokeform = StumpJokeForm()
        self.assertSequenceEqual(stumpjokeform.fields['most_recently_fooled'].queryset, [self.threepwood])

    def test_custom_field_with_queryset_but_no_limit_choices_to(self):
        """
        A custom field with a `queryset` attribute but no `limit_choices_to`
        works (#23795).
        """
        f = StumpJokeWithCustomFieldForm()
        self.assertEqual(f.fields['custom'].queryset, 42)

    def test_fields_for_model_applies_limit_choices_to(self):
        fields = fields_for_model(StumpJoke, ['has_fooled_today'])
        self.assertSequenceEqual(fields['has_fooled_today'].queryset, [self.threepwood])

    def test_callable_called_each_time_form_is_instantiated(self):
        field = StumpJokeForm.base_fields['most_recently_fooled']
        with mock.patch.object(field, 'limit_choices_to') as today_callable_dict:
            StumpJokeForm()
            self.assertEqual(today_callable_dict.call_count, 1)
            StumpJokeForm()
            self.assertEqual(today_callable_dict.call_count, 2)
            StumpJokeForm()
            self.assertEqual(today_callable_dict.call_count, 3)


class FormFieldCallbackTests(SimpleTestCase):

    def test_baseform_with_widgets_in_meta(self):
        """Regression for #13095: Using base forms with widgets defined in Meta should not raise errors."""
        widget = forms.Textarea()

        class BaseForm(forms.ModelForm):
            class Meta:
                model = Person
                widgets = {'name': widget}
                fields = "__all__"

        Form = modelform_factory(Person, form=BaseForm)
        self.assertIsInstance(Form.base_fields['name'].widget, forms.Textarea)

    def test_factory_with_widget_argument(self):
        """ Regression for #15315: modelform_factory should accept widgets
            argument
        """
        widget = forms.Textarea()

        # Without a widget should not set the widget to textarea
        Form = modelform_factory(Person, fields="__all__")
        self.assertNotEqual(Form.base_fields['name'].widget.__class__, forms.Textarea)

        # With a widget should not set the widget to textarea
        Form = modelform_factory(Person, fields="__all__", widgets={'name': widget})
        self.assertEqual(Form.base_fields['name'].widget.__class__, forms.Textarea)

    def test_modelform_factory_without_fields(self):
        """ Regression for #19733 """
        message = (
            "Calling modelform_factory without defining 'fields' or 'exclude' "
            "explicitly is prohibited."
        )
        with self.assertRaisesMessage(ImproperlyConfigured, message):
            modelform_factory(Person)

    def test_modelform_factory_with_all_fields(self):
        """ Regression for #19733 """
        form = modelform_factory(Person, fields="__all__")
        self.assertEqual(list(form.base_fields), ["name"])

    def test_custom_callback(self):
        """A custom formfield_callback is used if provided"""
        callback_args = []

        def callback(db_field, **kwargs):
            callback_args.append((db_field, kwargs))
            return db_field.formfield(**kwargs)

        widget = forms.Textarea()

        class BaseForm(forms.ModelForm):
            class Meta:
                model = Person
                widgets = {'name': widget}
                fields = "__all__"

        modelform_factory(Person, form=BaseForm, formfield_callback=callback)
        id_field, name_field = Person._meta.fields

        self.assertEqual(callback_args, [(id_field, {}), (name_field, {'widget': widget})])

    def test_bad_callback(self):
        # A bad callback provided by user still gives an error
        with self.assertRaises(TypeError):
            modelform_factory(Person, fields="__all__", formfield_callback='not a function or callable')

    def test_inherit_after_custom_callback(self):
        def callback(db_field, **kwargs):
            if isinstance(db_field, models.CharField):
                return forms.CharField(widget=forms.Textarea)
            return db_field.formfield(**kwargs)

        class BaseForm(forms.ModelForm):
            class Meta:
                model = Person
                fields = '__all__'

        NewForm = modelform_factory(Person, form=BaseForm, formfield_callback=callback)

        class InheritedForm(NewForm):
            pass

        for name in NewForm.base_fields:
            self.assertEqual(
                type(InheritedForm.base_fields[name].widget),
                type(NewForm.base_fields[name].widget)
            )


class LocalizedModelFormTest(TestCase):
    def test_model_form_applies_localize_to_some_fields(self):
        class PartiallyLocalizedTripleForm(forms.ModelForm):
            class Meta:
                model = Triple
                localized_fields = ('left', 'right',)
                fields = '__all__'

        f = PartiallyLocalizedTripleForm({'left': 10, 'middle': 10, 'right': 10})
        self.assertTrue(f.is_valid())
        self.assertTrue(f.fields['left'].localize)
        self.assertFalse(f.fields['middle'].localize)
        self.assertTrue(f.fields['right'].localize)

    def test_model_form_applies_localize_to_all_fields(self):
        class FullyLocalizedTripleForm(forms.ModelForm):
            class Meta:
                model = Triple
                localized_fields = '__all__'
                fields = '__all__'

        f = FullyLocalizedTripleForm({'left': 10, 'middle': 10, 'right': 10})
        self.assertTrue(f.is_valid())
        self.assertTrue(f.fields['left'].localize)
        self.assertTrue(f.fields['middle'].localize)
        self.assertTrue(f.fields['right'].localize)

    def test_model_form_refuses_arbitrary_string(self):
        msg = (
            "BrokenLocalizedTripleForm.Meta.localized_fields "
            "cannot be a string. Did you mean to type: ('foo',)?"
        )
        with self.assertRaisesMessage(TypeError, msg):
            class BrokenLocalizedTripleForm(forms.ModelForm):
                class Meta:
                    model = Triple
                    localized_fields = "foo"


class CustomMetaclass(ModelFormMetaclass):
    def __new__(cls, name, bases, attrs):
        new = super().__new__(cls, name, bases, attrs)
        new.base_fields = {}
        return new


class CustomMetaclassForm(forms.ModelForm, metaclass=CustomMetaclass):
    pass


class CustomMetaclassTestCase(SimpleTestCase):
    def test_modelform_factory_metaclass(self):
        new_cls = modelform_factory(Person, fields="__all__", form=CustomMetaclassForm)
        self.assertEqual(new_cls.base_fields, {})


class StrictAssignmentTests(TestCase):
    """
    Should a model do anything special with __setattr__() or descriptors which
    raise a ValidationError, a model form should catch the error (#24706).
    """

    def test_setattr_raises_validation_error_field_specific(self):
        """
        A model ValidationError using the dict form should put the error
        message into the correct key of form.errors.
        """
        form_class = modelform_factory(model=StrictAssignmentFieldSpecific, fields=['title'])
        form = form_class(data={'title': 'testing setattr'}, files=None)
        # This line turns on the ValidationError; it avoids the model erroring
        # when its own __init__() is called when creating form.instance.
        form.instance._should_error = True
        self.assertFalse(form.is_valid())
        self.assertEqual(form.errors, {
            'title': ['Cannot set attribute', 'This field cannot be blank.']
        })

    def test_setattr_raises_validation_error_non_field(self):
        """
        A model ValidationError not using the dict form should put the error
        message into __all__ (i.e. non-field errors) on the form.
        """
        form_class = modelform_factory(model=StrictAssignmentAll, fields=['title'])
        form = form_class(data={'title': 'testing setattr'}, files=None)
        # This line turns on the ValidationError; it avoids the model erroring
        # when its own __init__() is called when creating form.instance.
        form.instance._should_error = True
        self.assertFalse(form.is_valid())
        self.assertEqual(form.errors, {
            '__all__': ['Cannot set attribute'],
            'title': ['This field cannot be blank.']
        })


class ModelToDictTests(TestCase):
    def test_many_to_many(self):
        """Data for a ManyToManyField is a list rather than a lazy QuerySet."""
        blue = Colour.objects.create(name='blue')
        red = Colour.objects.create(name='red')
        item = ColourfulItem.objects.create()
        item.colours.set([blue])
        data = model_to_dict(item)['colours']
        self.assertEqual(data, [blue])
        item.colours.set([red])
        # If data were a QuerySet, it would be reevaluated here and give "red"
        # instead of the original value.
        self.assertEqual(data, [blue])
