Postgresql last_insert_id() failing when using custom schemas
|Reported by:||Anssi Kääriäinen||Owned by:||nobody|
|Component:||Database layer (models, ORM)||Version:||1.3|
|Has patch:||no||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
Define a table like this:
create sequence foobar; CREATE TABLE test ( id integer not null primary key default nextval('foobar') );
And a model like this:
class TestM(models.Model): pass class Meta: db_table = 'test'
In the shell, try this:
>>> t = TestM() >>> t.save() >>> t.id is None True
The error here is that postgresql's last_insert_id is defined like this:
def last_insert_id(self, cursor, table_name, pk_name): # Use pg_get_serial_sequence to get the underlying sequence name # from the table name and column name (available since PostgreSQL 8) cursor.execute("SELECT CURRVAL(pg_get_serial_sequence('%s','%s'))" % ( self.quote_name(table_name), pk_name)) return cursor.fetchone()
Now, what happens here is that pg_get_serial_sequence('test', 'id') will return NULL, and so will currval(NULL).
This is backwards incompatible as the same code would have worked in 1.2. Though I don't think it is documented anywhere that the above should work.
One possible fix is to throw an error if None is returned by cursor.fetchone() above and also document in the release notes that if you have a database defined like this, you should issue a query:
ALTER SEQUENCE foobar OWNED BY test, id;
This will unfortunately not work if the sequence is used by multiple tables, as a sequence can only be owned by one column at a time.
The best fix would be to allow setting the sequence name as an Meta option in the table (as in #13295), but it is way too late for 1.3.