Commit e8171daf authored by Collin Anderson's avatar Collin Anderson Committed by Tim Graham
Browse files

Fixed #24146 -- Fixed a missing fields regression in admin checks. 

This allows using get_field() early in the app loading process.

Thanks to PirosB3 and Tim Graham.
parent 8e8daf7c

django/db/models/options.py

+20 −8
Original line number Diff line number Diff line
@@ -487,6 +487,12 @@ class Options(object): 


    @cached_property

    def fields_map(self):

        return self._get_fields_map()



    def _get_fields_map(self):

        # Helper method to provide a way to access this without caching it.

        # For example, admin checks run before the app cache is ready and we

        # need to be able to lookup fields before we cache the final result.

        res = {}

        fields = self._get_fields(forward=False, include_hidden=True)

        for field in fields:
@@ -531,20 +537,26 @@ class Options(object): 


            return field

        except KeyError:

            # If the app registry is not ready, reverse fields are

            # unavailable, therefore we throw a FieldDoesNotExist exception.

            pass



        if m2m_in_kwargs:

            # Previous API does not allow searching reverse fields.

            raise FieldDoesNotExist('%s has no field named %r' % (self.object_name, field_name))



        # If the app registry is not ready, reverse fields are probably

        # unavailable, but try anyway.

        if not self.apps.ready:

            try:

                # Don't cache results

                return self._get_fields_map()[field_name]

            except KeyError:

                raise FieldDoesNotExist(

                    "%s has no field named %r. The app cache isn't ready yet, "

                    "so if this is an auto-created related field, it won't "

                    "so if this is an auto-created related field, it might not "

                    "be available yet." % (self.object_name, field_name)

                )



        try:

            if m2m_in_kwargs:

                # Previous API does not allow searching reverse fields.

                raise FieldDoesNotExist('%s has no field named %r' % (self.object_name, field_name))



            # Retrieve field instance by name from cached or just-computed

            # field map.

            return self.fields_map[field_name]

tests/model_meta/tests.py

+11 −5
Original line number Diff line number Diff line
@@ -169,24 +169,30 @@ class GetFieldByNameTests(OptionsBaseTests): 
        self.assertEqual(field_info[1:], (None, True, False))

        self.assertIsInstance(field_info[0], GenericRelation)



    def test_get_fields_only_searches_forward_on_apps_not_ready(self):

    def test_get_fields_when_apps_not_ready(self):

        opts = Person._meta

        # If apps registry is not ready, get_field() searches over only

        # forward fields.

        opts.apps.ready = False

        # Clear cached data.

        opts.__dict__.pop('fields_map', None)

        try:

            # 'data_abstract' is a forward field, and therefore will be found

            self.assertTrue(opts.get_field('data_abstract'))

            msg = (

                "Person has no field named 'relating_baseperson'. The app "

                "Person has no field named 'some_missing_field'. The app "

                "cache isn't ready yet, so if this is an auto-created related "

                "field, it won't be available yet."

                "field, it might not be available yet."

            )

            # 'data_abstract' is a reverse field, and will raise an exception

            with self.assertRaisesMessage(FieldDoesNotExist, msg):

                opts.get_field('relating_baseperson')

                opts.get_field('some_missing_field')

            # Be sure it's not cached

            self.assertNotIn('fields_map', opts.__dict__)

        finally:

            opts.apps.ready = True

        # At this point searching a related field would cache fields_map

        opts.get_field('relating_baseperson')

        self.assertIn('fields_map', opts.__dict__)





class RelationTreeTests(TestCase):