Commit 202bf69c authored by Andrew Gorcester's avatar Andrew Gorcester Committed by Baptiste Mispelon
Browse files

Fixed #22095 -- Enabled backward migrations for RunPython operations 

Added reversible property to RunPython so that migrations will not
refuse to reverse migrations including RunPython operations, so long as
reverse_code is set in the RunPython constructor. Included tests to
check the reversible property on RunPython and the similar RunSQL.
parent b8874084

django/db/migrations/operations/special.py

+4 −1
Original line number Diff line number Diff line
@@ -103,7 +103,6 @@ class RunPython(Operation): 
    """



    reduces_to_sql = False

    reversible = False



    def __init__(self, code, reverse_code=None):

        # Forwards code
@@ -118,6 +117,10 @@ class RunPython(Operation): 
                raise ValueError("RunPython must be supplied with callable arguments")

            self.reverse_code = reverse_code



    @property

    def reversible(self):

        return self.reverse_code is not None



    def state_forwards(self, app_label, state):

        # RunPython objects have no state effect. To add some, combine this

        # with SeparateDatabaseAndState.

tests/migrations/test_operations.py

+20 −4
Original line number Diff line number Diff line
@@ -468,6 +468,7 @@ class OperationTests(MigrationTestBase): 
            operation.database_forwards("test_runsql", editor, project_state, new_state)

        self.assertTableExists("i_love_ponies")

        # And test reversal

        self.assertTrue(operation.reversible)

        with connection.schema_editor() as editor:

            operation.database_backwards("test_runsql", editor, new_state, project_state)

        self.assertTableNotExists("i_love_ponies")
@@ -484,7 +485,11 @@ class OperationTests(MigrationTestBase): 
            Pony = models.get_model("test_runpython", "Pony")

            Pony.objects.create(pink=1, weight=3.55)

            Pony.objects.create(weight=5)

        operation = migrations.RunPython(inner_method)

        def inner_method_reverse(models, schema_editor):

            Pony = models.get_model("test_runpython", "Pony")

            Pony.objects.filter(pink=1, weight=3.55).delete()

            Pony.objects.filter(weight=5).delete()

        operation = migrations.RunPython(inner_method, reverse_code=inner_method_reverse)

        # Test the state alteration does nothing

        new_state = project_state.clone()

        operation.state_forwards("test_runpython", new_state)
@@ -494,13 +499,24 @@ class OperationTests(MigrationTestBase): 
        with connection.schema_editor() as editor:

            operation.database_forwards("test_runpython", editor, project_state, new_state)

        self.assertEqual(project_state.render().get_model("test_runpython", "Pony").objects.count(), 2)

        # And test reversal fails

        with self.assertRaises(NotImplementedError):

            operation.database_backwards("test_runpython", None, new_state, project_state)

        # Now test reversal

        self.assertTrue(operation.reversible)

        with connection.schema_editor() as editor:

            operation.database_backwards("test_runpython", editor, project_state, new_state)

        self.assertEqual(project_state.render().get_model("test_runpython", "Pony").objects.count(), 0)

        # Now test we can't use a string

        with self.assertRaises(ValueError):

            operation = migrations.RunPython("print 'ahahaha'")



        # Also test reversal fails, with an operation identical to above but without reverse_code set

        no_reverse_operation = migrations.RunPython(inner_method)

        self.assertFalse(no_reverse_operation.reversible)

        with connection.schema_editor() as editor:

            no_reverse_operation.database_forwards("test_runpython", editor, project_state, new_state)

            with self.assertRaises(NotImplementedError):

                no_reverse_operation.database_backwards("test_runpython", editor, new_state, project_state)







class MigrateNothingRouter(object):

    """