[1.7.x] Fixed #22875: Optimizer did not take through= into account. (aa0886e7) · Commits · Dom Sekotill / django

django/db/migrations/optimizer.py

+20 −5

Original line number	Diff line number	Diff line
		@@ -160,6 +160,19 @@ class MigrationOptimizer(object):
		return om(operation, other, in_between or [])
		return None

		def model_to_key(self, model):
		"""
		Takes either a model class or a "appname.ModelName" string
		and returns (appname, modelname)
		"""
		if isinstance(model, six.string_types):
		return model.split(".", 1)
		else:
		return (
		model._meta.app_label,
		model._meta.object_name,
		)

		def reduce_model_create_delete(self, operation, other, in_between):
		"""
		Folds a CreateModel and a DeleteModel into nothing.
		@@ -206,11 +219,13 @@ class MigrationOptimizer(object):
		# Don't allow optimisations of FKs through models they reference
		if hasattr(other.field, "rel") and other.field.rel:
		for between in in_between:
		if isinstance(other.field.rel.to, six.string_types):
		object_name, app_label = other.field.rel.to.split(".", 1)
		else:
		object_name = other.field.rel.to._meta.object_name
		app_label = other.field.rel.to._meta.app_label
		# Check that it doesn't point to the model
		app_label, object_name = self.model_to_key(other.field.rel.to)
		if between.references_model(object_name, app_label):
		return None
		# Check that it's not through the model
		if getattr(other.field.rel, "through", None):
		app_label, object_name = self.model_to_key(other.field.rel.through)
		if between.references_model(object_name, app_label):
		return None
		# OK, that's fine

tests/migrations/test_optimizer.py

+38 −0

Original line number	Diff line number	Diff line
		@@ -201,6 +201,44 @@ class OptimizerTests(TestCase):
		],
		)

		def test_create_model_add_field_not_through_fk(self):
		"""
		AddField should NOT optimize into CreateModel if it's an FK to a model
		that's between them.
		"""
		self.assertOptimizesTo(
		[
		migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]),
		migrations.CreateModel("Link", [("url", models.TextField())]),
		migrations.AddField("Foo", "link", models.ForeignKey("migrations.Link")),
		],
		[
		migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]),
		migrations.CreateModel("Link", [("url", models.TextField())]),
		migrations.AddField("Foo", "link", models.ForeignKey("migrations.Link")),
		],
		)

		def test_create_model_add_field_not_through_m2m_through(self):
		"""
		AddField should NOT optimize into CreateModel if it's an M2M using a
		through that's created between them.
		"""
		# Note: The middle model is not actually a valid through model,
		# but that doesn't matter, as we never render it.
		self.assertOptimizesTo(
		[
		migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]),
		migrations.CreateModel("LinkThrough", []),
		migrations.AddField("Foo", "link", models.ManyToManyField("migrations.Link", through="migrations.LinkThrough")),
		],
		[
		migrations.CreateModel("Foo", [("name", models.CharField(max_length=255))]),
		migrations.CreateModel("LinkThrough", []),
		migrations.AddField("Foo", "link", models.ManyToManyField("migrations.Link", through="migrations.LinkThrough")),
		],
		)

		def test_create_model_alter_field(self):
		"""
		AlterField should optimize into CreateModel.