Fixed #22935 -- Changed ForeignKey.default_error_messages['invalid'] to refer to correct field.

Thanks Tim Graham for suggestion and review.

django/db/models/fields/related.py

@@ -1600,7 +1600,7 @@ class ForeignObject(RelatedField):
 class ForeignKey(ForeignObject):
     empty_strings_allowed = False
     default_error_messages = {
-        'invalid': _('%(model)s instance with pk %(pk)r does not exist.')
+        'invalid': _('%(model)s instance with %(field)s %(value)r does not exist.')
     }
     description = _("Foreign Key (type determined by related field)")
 
@@ -1707,7 +1707,10 @@ class ForeignKey(ForeignObject):
             raise exceptions.ValidationError(
                 self.error_messages['invalid'],
                 code='invalid',
-                params={'model': self.rel.to._meta.verbose_name, 'pk': value},
+                params={
+                    'model': self.rel.to._meta.verbose_name, 'pk': value,
+                    'field': self.rel.field_name, 'value': value,
+                },  # 'pk' is included for backwards compatibilty
             )
 
     def get_attname(self):

docs/releases/1.8.txt

@@ -391,6 +391,13 @@ Miscellaneous
 
 * Support for SpatiaLite < 2.4 has been dropped.
 
+* ``ForeignKey.default_error_message['invalid']`` has been changed from
+  ``'%(model)s instance with pk %(pk)r does not exist.'`` to
+  ``'%(model)s instance with %(field)s %(value)r does not exist.'`` If you are
+  using this message in your own code, please update the list of interpolated
+  parameters. Internally, Django will continue to provide the
+  ``pk`` parameter in ``params`` for backwards compatibility.
+
 .. _deprecated-features-1.8:
 
 Features deprecated in 1.8

tests/validation/models.py

@@ -18,6 +18,7 @@ class ModelToValidate(models.Model):
     number = models.IntegerField(db_column='number_val')
     parent = models.ForeignKey('self', blank=True, null=True, limit_choices_to={'number': 10})
     email = models.EmailField(blank=True)
+    ufm = models.ForeignKey('UniqueFieldsModel', to_field='unique_charfield', blank=True, null=True)
     url = models.URLField(blank=True)
     f_with_custom_validator = models.IntegerField(blank=True, null=True, validators=[validate_answer_to_universe])
     slug = models.SlugField(blank=True)

tests/validation/tests.py

@@ -25,7 +25,12 @@ class BaseModelValidationTests(ValidationTestCase):
 
     def test_wrong_FK_value_raises_error(self):
         mtv = ModelToValidate(number=10, name='Some Name', parent_id=3)
-        self.assertFailsValidation(mtv.full_clean, ['parent'])
+        self.assertFieldFailsValidationWithMessage(mtv.full_clean, 'parent',
+            ['model to validate instance with id %r does not exist.' % mtv.parent_id])
+
+        mtv = ModelToValidate(number=10, name='Some Name', ufm_id='Some Name')
+        self.assertFieldFailsValidationWithMessage(mtv.full_clean, 'ufm',
+            ["unique fields model instance with unique_charfield %r does not exist." % mtv.name])
 
     def test_correct_FK_value_validates(self):
         parent = ModelToValidate.objects.create(number=10, name='Some Name')