Commit 21130ce1 authored by Sergey Fedoseev's avatar Sergey Fedoseev Committed by Tim Graham
Browse files

Fixed #26718 -- Added system check for existence of the fields specified by ForeignKey.to_field.

parent f6681393

django/db/models/fields/related.py

+23 −0
Original line number Diff line number Diff line
@@ -463,9 +463,32 @@ class ForeignObject(RelatedField): 


    def check(self, **kwargs):

        errors = super(ForeignObject, self).check(**kwargs)

        errors.extend(self._check_to_fields_exist())

        errors.extend(self._check_unique_target())

        return errors



    def _check_to_fields_exist(self):

        # Skip nonexistent models.

        if isinstance(self.remote_field.model, six.string_types):

            return []



        errors = []

        for to_field in self.to_fields:

            if to_field:

                try:

                    self.remote_field.model._meta.get_field(to_field)

                except exceptions.FieldDoesNotExist:

                    errors.append(

                        checks.Error(

                            "The to_field '%s' doesn't exist on the related "

                            "model '%s'."

                            % (to_field, self.remote_field.model._meta.label),

                            obj=self,

                            id='fields.E312',

                        )

                    )

        return errors



    def _check_unique_target(self):

        rel_is_string = isinstance(self.remote_field.model, six.string_types)

        if rel_is_string or not self.requires_unique_target:

docs/ref/checks.txt

+2 −0
Original line number Diff line number Diff line
@@ -211,6 +211,8 @@ Related Fields 
  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.E312**: The ``to_field`` ``<field name>`` doesn't exist on the

  related model ``<app label>.<model>``.

* **fields.E320**: Field specifies ``on_delete=SET_NULL``, but cannot be null.

* **fields.E321**: The field specifies ``on_delete=SET_DEFAULT``, but has no

  default value.

tests/invalid_models_tests/test_relative_fields.py

+50 −0
Original line number Diff line number Diff line
@@ -763,6 +763,56 @@ class RelativeFieldTests(SimpleTestCase): 
            errors = Child.check()

            self.assertFalse(errors)



    def test_to_fields_exist(self):

        class Parent(models.Model):

            pass



        class Child(models.Model):

            a = models.PositiveIntegerField()

            b = models.PositiveIntegerField()

            parent = ForeignObject(

                Parent,

                on_delete=models.SET_NULL,

                from_fields=('a', 'b'),

                to_fields=('a', 'b'),

            )



        field = Child._meta.get_field('parent')

        expected = [

            Error(

                "The to_field 'a' doesn't exist on the related model 'invalid_models_tests.Parent'.",

                obj=field,

                id='fields.E312',

            ),

            Error(

                "The to_field 'b' doesn't exist on the related model 'invalid_models_tests.Parent'.",

                obj=field,

                id='fields.E312',

            ),

        ]

        self.assertEqual(field.check(), expected)



    def test_to_fields_not_checked_if_related_model_doesnt_exist(self):

        class Child(models.Model):

            a = models.PositiveIntegerField()

            b = models.PositiveIntegerField()

            parent = ForeignObject(

                'invalid_models_tests.Parent',

                on_delete=models.SET_NULL,

                from_fields=('a', 'b'),

                to_fields=('a', 'b'),

            )



        field = Child._meta.get_field('parent')

        self.assertEqual(field.check(), [

            Error(

                "Field defines a relation with model 'invalid_models_tests.Parent', "

                "which is either not installed, or is abstract.",

                id='fields.E300',

                obj=field,

            ),

        ])





@isolate_apps('invalid_models_tests')

class AccessorClashTests(SimpleTestCase):