Commit a9da5dd5 authored by Tim Graham's avatar Tim Graham
Browse files

[1.7.x] Fixed #23581 -- Prevented extraneous DROP DEFAULT statements. 

Thanks john_scott for the report and Markus Holtermann for review.

Backport of ab4f709d from master
parent 79645529

django/db/backends/schema.py

+20 −23
Original line number Diff line number Diff line
@@ -534,15 +534,12 @@ class BaseDatabaseSchemaEditor(object): 
        # Default change?

        old_default = self.effective_default(old_field)

        new_default = self.effective_default(new_field)

        if old_default != new_default and not self.skip_default(new_field):

            if new_default is None:

                actions.append((

                    self.sql_alter_column_no_default % {

                        "column": self.quote_name(new_field.column),

                    },

                    [],

                ))

            else:

        needs_database_default = (

            old_default != new_default and

            new_default is not None and

            not self.skip_default(new_field)

        )

        if needs_database_default:

            if self.connection.features.requires_literal_defaults:

                # Some databases can't take defaults as a parameter (oracle)

                # If this is the case, the individual schema backend should
@@ -696,7 +693,7 @@ class BaseDatabaseSchemaEditor(object): 
            )

        # Drop the default if we need to

        # (Django usually does not use in-database defaults)

        if not self.skip_default(new_field) and new_field.default is not None:

        if needs_database_default:

            sql = self.sql_alter_column % {

                "table": self.quote_name(model._meta.db_table),

                "changes": self.sql_alter_column_no_default % {

docs/releases/1.7.2.txt

+2 −0
Original line number Diff line number Diff line
@@ -181,3 +181,5 @@ Bugfixes 


* Supported strings escaped by third-party libraries with the ``__html__``

  convention in the template engine (:ticket:`23831`).



* Prevented extraneous ``DROP DEFAULT`` SQL in migrations (:ticket:`23581`).

tests/schema/tests.py

+4 −0
Original line number Diff line number Diff line
@@ -554,6 +554,10 @@ class SchemaTests(TransactionTestCase): 
                strict=True,

            )



        # This will fail if DROP DEFAULT is inadvertently executed on this

        # field which drops the id sequence, at least on PostgreSQL.

        Author.objects.create(name='Foo')



    def test_rename(self):

        """

        Tests simple altering of fields