Commit 7a38f889 authored by Simon Charette's avatar Simon Charette
Browse files

Fixed #22659 -- Prevent model states from sharing field instances. 

Thanks to Trac alias tbartelmess for the report and the test project.
parent f384b638

django/db/migrations/state.py

+14 −8
Original line number Diff line number Diff line
@@ -143,6 +143,12 @@ class ModelState(object): 
        # Sanity-check that fields is NOT a dict. It must be ordered.

        if isinstance(self.fields, dict):

            raise ValueError("ModelState.fields cannot be a dict - it must be a list of 2-tuples.")

        # Sanity-check that fields are NOT already bound to a model.

        for name, field in fields:

            if hasattr(field, 'model'):

                raise ValueError(

                    'ModelState.fields cannot be bound to a model - "%s" is.' % name

                )



    @classmethod

    def from_model(cls, model):
@@ -226,19 +232,19 @@ class ModelState(object): 
            bases,

        )



    def clone(self):

        "Returns an exact copy of this ModelState"

        # We deep-clone the fields using deconstruction

        fields = []

    def construct_fields(self):

        "Deep-clone the fields using deconstruction"

        for name, field in self.fields:

            _, path, args, kwargs = field.deconstruct()

            field_class = import_string(path)

            fields.append((name, field_class(*args, **kwargs)))

        # Now make a copy

            yield name, field_class(*args, **kwargs)



    def clone(self):

        "Returns an exact copy of this ModelState"

        return self.__class__(

            app_label=self.app_label,

            name=self.name,

            fields=fields,

            fields=list(self.construct_fields()),

            options=dict(self.options),

            bases=self.bases,

        )
@@ -260,7 +266,7 @@ class ModelState(object): 
        except LookupError:

            raise InvalidBasesError("Cannot resolve one or more bases from %r" % (self.bases,))

        # Turn fields into a dict for the body, add other bits

        body = dict(self.fields)

        body = dict(self.construct_fields())

        body['Meta'] = meta

        body['__module__'] = "__fake__"

        # Then, make a Model object

tests/migrations/test_autodetector.py

+2 −2
Original line number Diff line number Diff line
@@ -241,7 +241,7 @@ class AutodetectorTests(TestCase): 
        action = migration.operations[0]

        self.assertEqual(action.__class__.__name__, "AlterField")

        self.assertEqual(action.name, "author")

        self.assertEqual(action.field.rel.to.__name__, "Writer")

        self.assertEqual(action.field.rel.to, "testapp.Writer")



    def test_rename_model_with_renamed_rel_field(self):

        """
@@ -278,7 +278,7 @@ class AutodetectorTests(TestCase): 
        action = migration.operations[1]

        self.assertEqual(action.__class__.__name__, "AlterField")

        self.assertEqual(action.name, "writer")

        self.assertEqual(action.field.rel.to.__name__, "Writer")

        self.assertEqual(action.field.rel.to, "testapp.Writer")



    def test_fk_dependency(self):

        "Tests that having a ForeignKey automatically adds a dependency"

tests/migrations/test_state.py

+18 −1
Original line number Diff line number Diff line
@@ -356,7 +356,7 @@ class StateTests(TestCase): 
        project_state = ProjectState()

        project_state.add_model_state(ModelState.from_model(TestModel))

        with self.assertRaises(ValueError):

            rendered_state = project_state.render()

            project_state.render()



        # If we include the real app it should succeed

        project_state = ProjectState(real_apps=["contenttypes"])
@@ -372,3 +372,20 @@ class ModelStateTests(TestCase): 
    def test_custom_model_base(self):

        state = ModelState.from_model(ModelWithCustomBase)

        self.assertEqual(state.bases, (models.Model,))



    def test_bound_field_sanity_check(self):

        field = models.CharField(max_length=1)

        field.model = models.Model

        with self.assertRaisesMessage(ValueError,

                'ModelState.fields cannot be bound to a model - "field" is.'):

            ModelState('app', 'Model', [('field', field)])



    def test_fields_immutability(self):

        """

        Tests that rendering a model state doesn't alter its internal fields.

        """

        apps = Apps()

        field = models.CharField(max_length=1)

        state = ModelState('app', 'Model', [('name', field)])

        Model = state.render(apps)

        self.assertNotEqual(Model._meta.get_field('name'), field)