Fixed #27015 -- Prevented HTML-invalid minlength/maxlength on hidden inputs

django/forms/fields.py

@@ -236,10 +236,10 @@ class CharField(Field):
 
     def widget_attrs(self, widget):
         attrs = super(CharField, self).widget_attrs(widget)
-        if self.max_length is not None:
+        if self.max_length is not None and not widget.is_hidden:
             # The HTML attribute is maxlength, not max_length.
             attrs['maxlength'] = str(self.max_length)
-        if self.min_length is not None:
+        if self.min_length is not None and not widget.is_hidden:
             # The HTML attribute is minlength, not min_length.
             attrs['minlength'] = str(self.min_length)
         return attrs

tests/forms_tests/field_tests/test_charfield.py

 from __future__ import unicode_literals
 
 from django.forms import (
-    CharField, PasswordInput, Textarea, TextInput, ValidationError,
+    CharField, HiddenInput, PasswordInput, Textarea, TextInput, ValidationError,
 )
 from django.test import SimpleTestCase
 
@@ -79,7 +79,9 @@ class CharFieldTest(FormFieldAssertionsMixin, SimpleTestCase):
 
     def test_charfield_widget_attrs(self):
         """
-        CharField.widget_attrs() always returns a dictionary (#15912).
+        CharField.widget_attrs() always returns a dictionary and includes
+        minlength/maxlength if min_length/max_length are defined on the field
+        and the widget is not hidden.
         """
         # Return an empty dictionary if max_length and min_length are both None.
         f = CharField()
@@ -104,6 +106,7 @@ class CharFieldTest(FormFieldAssertionsMixin, SimpleTestCase):
         self.assertEqual(f.widget_attrs(TextInput()), {'maxlength': '10', 'minlength': '5'})
         self.assertEqual(f.widget_attrs(PasswordInput()), {'maxlength': '10', 'minlength': '5'})
         self.assertEqual(f.widget_attrs(Textarea()), {'maxlength': '10', 'minlength': '5'})
+        self.assertEqual(f.widget_attrs(HiddenInput()), {})
 
     def test_charfield_strip(self):
         """