Fixed #22073 - Ensure CreateTable operation handles backwards migration... (df2652c4) · Commits · Dom Sekotill / django

django/db/backends/schema.py

+5 −0

Original line number	Diff line number	Diff line
		@@ -268,6 +268,11 @@ class BaseDatabaseSchemaEditor(object):
		"""
		Deletes a model from the database.
		"""
		# Handle auto-created intermediary models
		for field in model._meta.local_many_to_many:
		if field.rel.through._meta.auto_created:
		self.delete_model(field.rel.through)

		# Delete the table
		self.execute(self.sql_delete_table % {
		"table": self.quote_name(model._meta.db_table),

tests/migrations/test_operations.py

+40 −0

Original line number	Diff line number	Diff line
		@@ -90,6 +90,46 @@ class OperationTests(MigrationTestBase):
		self.assertEqual(len(definition[2]), 0)
		self.assertEqual(definition[1][0], "Pony")

		def test_create_model_m2m(self):
		"""
		Test the creation of a model with a ManyToMany field and the
		auto-created "through" model.
		"""
		project_state = self.set_up_test_model("test_crmomm")
		operation = migrations.CreateModel(
		"Stable",
		[
		("id", models.AutoField(primary_key=True)),
		("ponies", models.ManyToManyField("Pony", related_name="stables"))
		]
		)
		# Test the state alteration
		new_state = project_state.clone()
		operation.state_forwards("test_crmomm", new_state)
		# Test the database alteration
		self.assertTableNotExists("test_crmomm_stable_ponies")
		with connection.schema_editor() as editor:
		operation.database_forwards("test_crmomm", editor, project_state, new_state)
		self.assertTableExists("test_crmomm_stable")
		self.assertTableExists("test_crmomm_stable_ponies")
		self.assertColumnNotExists("test_crmomm", "ponies")
		# Make sure the M2M field actually works
		with atomic():
		new_apps = new_state.render()
		Pony = new_apps.get_model("test_crmomm", "Pony")
		Stable = new_apps.get_model("test_crmomm", "Stable")
		stable = Stable.objects.create()
		p1 = Pony.objects.create(pink=False, weight=4.55)
		p2 = Pony.objects.create(pink=True, weight=5.43)
		stable.ponies.add(p1, p2)
		self.assertEqual(stable.ponies.count(), 2)
		stable.ponies.all().delete()
		# And test reversal
		with connection.schema_editor() as editor:
		operation.database_backwards("test_crmomm", editor, new_state, project_state)
		self.assertTableNotExists("test_crmomm_stable")
		self.assertTableNotExists("test_crmomm_stable_ponies")

		def test_create_model_inheritance(self):
		"""
		Tests the CreateModel operation on a multi-table inheritance setup.