Commit 1edfa155 authored by Daniel Hahler's avatar Daniel Hahler Committed by Tim Graham
Browse files

Fixed #22293 -- Avoided renaming many-to-many tables to themselves. 

Fixed this for both implementations of _alter_many_to_many, instead of
in `alter_db_table` itself (more implementations).
parent d81a9c50

django/db/backends/schema.py

+2 −1
Original line number Diff line number Diff line
@@ -762,6 +762,7 @@ class BaseDatabaseSchemaEditor(object): 
        Alters M2Ms to repoint their to= endpoints.

        """

        # Rename the through table

        if old_field.rel.through._meta.db_table != new_field.rel.through._meta.db_table:

            self.alter_db_table(old_field.rel.through, old_field.rel.through._meta.db_table, new_field.rel.through._meta.db_table)

        # Repoint the FK to the other side

        self.alter_field(

django/db/backends/sqlite3/schema.py

+3 −0
Original line number Diff line number Diff line
@@ -161,6 +161,9 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor): 
        """

        Alters M2Ms to repoint their to= endpoints.

        """

        if old_field.rel.through == new_field.rel.through:

            return



        # Make a new through table

        self.create_model(new_field.rel.through)

        # Copy the data across

tests/schema/tests.py

+9 −0
Original line number Diff line number Diff line
@@ -347,6 +347,15 @@ class SchemaTests(TransactionTestCase): 
            # Ensure there is now an m2m table there

            columns = self.column_classes(new_field.rel.through)

            self.assertEqual(columns['tagm2mtest_id'][0], "IntegerField")



            # "Alter" the field. This should not rename the DB table to itself.

            with connection.schema_editor() as editor:

                editor.alter_field(

                    Author,

                    new_field,

                    new_field,

                )



            # Remove the M2M table again

            with connection.schema_editor() as editor:

                editor.remove_field(