Refs #25535 -- Minor edits to ForeignObject check changes.

django/db/models/fields/related.py

@@ -474,7 +474,6 @@ class ForeignObject(RelatedField):
             for ut in self.remote_field.model._meta.unique_together
         })
         foreign_fields = {f.name for f in self.foreign_related_fields}
-
         has_unique_constraint = any(u <= foreign_fields for u in unique_foreign_fields)
 
         if not has_unique_constraint and len(self.foreign_related_fields) > 1:
@@ -483,11 +482,12 @@ class ForeignObject(RelatedField):
             model_name = self.remote_field.model.__name__
             return [
                 checks.Error(
-                    "No subset of the fields %s on model '%s' is unique"
+                    "No subset of the fields %s on model '%s' is unique."
                     % (field_combination, model_name),
-                    hint="Add a unique=True on any of the fields %s of '%s', or add them all or a "
-                         "subset to a unique_together constraint."
-                         % (field_combination, model_name),
+                    hint=(
+                        "Add unique=True on any of those fields or add at "
+                        "least a subset of them to a unique_together constraint."
+                    ),
                     obj=self,
                     id='fields.E310',
                 )

docs/ref/checks.txt

@@ -189,8 +189,9 @@ Related Fields
   for ``<field name>``.
 * **fields.E306**: Related name must be a valid Python identifier or end with
   a ``'+'``.
-* **fields.E310**: None of the fields ``<field1>``, ``<field2>``, ... on model
-  ``<model>`` have a ``unique=True`` constraint.
+* **fields.E310**: No subset of the fields ``<field1>``, ``<field2>``, ... on
+  model ``<model>`` is unique. Add ``unique=True`` on any of those fields or
+  add at least a subset of them to a unique_together constraint.
 * **fields.E311**: ``<model>`` must set ``unique=True`` because it is
   referenced by a ``ForeignKey``.
 * **fields.E320**: Field specifies ``on_delete=SET_NULL``, but cannot be null.

tests/foreign_object/tests.py

@@ -4,7 +4,7 @@ from operator import attrgetter
 from django.core.exceptions import FieldError
 from django.db import models
 from django.db.models.fields.related import ForeignObject
-from django.test import TestCase, skipUnlessDBFeature
+from django.test import SimpleTestCase, TestCase, skipUnlessDBFeature
 from django.utils import translation
 
 from .models import (
@@ -394,21 +394,21 @@ class MultiColumnFKTests(TestCase):
         objs = [Person(name="abcd_%s" % i, person_country=self.usa) for i in range(0, 5)]
         Person.objects.bulk_create(objs, 10)
 
+
+class TestModelCheckTests(SimpleTestCase):
+
     def test_check_composite_foreign_object(self):
         class Parent(models.Model):
             a = models.PositiveIntegerField()
             b = models.PositiveIntegerField()
 
             class Meta:
-                unique_together = (
-                    ('a', 'b'),
-                )
+                unique_together = (('a', 'b'),)
 
         class Child(models.Model):
             a = models.PositiveIntegerField()
             b = models.PositiveIntegerField()
             value = models.CharField(max_length=255)
-
             parent = ForeignObject(
                 Parent,
                 on_delete=models.SET_NULL,
@@ -417,10 +417,7 @@ class MultiColumnFKTests(TestCase):
                 related_name='children',
             )
 
-        field = Child._meta.get_field('parent')
-        errors = field.check(from_model=Child)
-
-        self.assertEqual(errors, [])
+        self.assertEqual(Child._meta.get_field('parent').check(from_model=Child), [])
 
     def test_check_subset_composite_foreign_object(self):
         class Parent(models.Model):
@@ -429,16 +426,13 @@ class MultiColumnFKTests(TestCase):
             c = models.PositiveIntegerField()
 
             class Meta:
-                unique_together = (
-                    ('a', 'b'),
-                )
+                unique_together = (('a', 'b'),)
 
         class Child(models.Model):
             a = models.PositiveIntegerField()
             b = models.PositiveIntegerField()
             c = models.PositiveIntegerField()
             d = models.CharField(max_length=255)
-
             parent = ForeignObject(
                 Parent,
                 on_delete=models.SET_NULL,
@@ -447,7 +441,4 @@ class MultiColumnFKTests(TestCase):
                 related_name='children',
             )
 
-        field = Child._meta.get_field('parent')
-        errors = field.check(from_model=Child)
-
-        self.assertEqual(errors, [])
+        self.assertEqual(Child._meta.get_field('parent').check(from_model=Child), [])

tests/invalid_models_tests/test_relative_fields.py

@@ -508,9 +508,11 @@ class RelativeFieldTests(IsolatedModelsTestCase):
         errors = field.check()
         expected = [
             Error(
-                "No subset of the fields 'country_id', 'city_id' on model 'Person' is unique",
-                hint="Add a unique=True on any of the fields 'country_id', 'city_id' of 'Person', "
-                     "or add them all or a subset to a unique_together constraint.",
+                "No subset of the fields 'country_id', 'city_id' on model 'Person' is unique.",
+                hint=(
+                    "Add unique=True on any of those fields or add at least "
+                    "a subset of them to a unique_together constraint."
+                ),
                 obj=field,
                 id='fields.E310',
             )
@@ -1404,15 +1406,12 @@ class M2mThroughFieldsTests(IsolatedModelsTestCase):
             c = models.PositiveIntegerField()
 
             class Meta:
-                unique_together = (
-                    ('a', 'b', 'c'),
-                )
+                unique_together = (('a', 'b', 'c'),)
 
         class Child(models.Model):
             a = models.PositiveIntegerField()
             b = models.PositiveIntegerField()
             value = models.CharField(max_length=255)
-
             parent = ForeignObject(
                 Parent,
                 on_delete=models.SET_NULL,
@@ -1425,9 +1424,11 @@ class M2mThroughFieldsTests(IsolatedModelsTestCase):
         errors = field.check(from_model=Child)
         expected = [
             Error(
-                "No subset of the fields 'a', 'b' on model 'Parent' is unique",
-                hint="Add a unique=True on any of the fields 'a', 'b' of 'Parent', or add them "
-                     "all or a subset to a unique_together constraint.",
+                "No subset of the fields 'a', 'b' on model 'Parent' is unique.",
+                hint=(
+                    "Add unique=True on any of those fields or add at least "
+                    "a subset of them to a unique_together constraint."
+                ),
                 obj=field,
                 id='fields.E310',
             ),
@@ -1442,16 +1443,13 @@ class M2mThroughFieldsTests(IsolatedModelsTestCase):
             d = models.PositiveIntegerField()
 
             class Meta:
-                unique_together = (
-                    ('a', 'b', 'c'),
-                )
+                unique_together = (('a', 'b', 'c'),)
 
         class Child(models.Model):
             a = models.PositiveIntegerField()
             b = models.PositiveIntegerField()
             d = models.PositiveIntegerField()
             value = models.CharField(max_length=255)
-
             parent = ForeignObject(
                 Parent,
                 on_delete=models.SET_NULL,
@@ -1464,9 +1462,11 @@ class M2mThroughFieldsTests(IsolatedModelsTestCase):
         errors = field.check(from_model=Child)
         expected = [
             Error(
-                "No subset of the fields 'a', 'b', 'd' on model 'Parent' is unique",
-                hint="Add a unique=True on any of the fields 'a', 'b', 'd' of 'Parent', or add "
-                     "them all or a subset to a unique_together constraint.",
+                "No subset of the fields 'a', 'b', 'd' on model 'Parent' is unique.",
+                hint=(
+                    "Add unique=True on any of those fields or add at least "
+                    "a subset of them to a unique_together constraint."
+                ),
                 obj=field,
                 id='fields.E310',
             ),