On Wed, 2009-05-13 at 12:49 -0400, J. Cliff Dyer wrote:
> Setup:
>
> Ubuntu 9.04
> Python 2.6.2
> Django 1.0.2
> Postgres 8.3.7
> postgresql-psycopg2
>
> I'm having issues using ./manage.py syncdb and ./manage.py flush with a
> project of mine. I've got an app, venues, which defines a
> ManyToManyField.
>
> After syncdb loads the fixtures, (and only if it tries to load fixtures)
> it hits the following error:
>
> {{{
> [...]
> Installing json fixture 'initial_data' from
> '/cgi/django/apps/cdla_apps/venues/fixtures'.
> Traceback (most recent call last):
> File "./manage.py", line 11, in <module>
> execute_manager(settings)
> File
> "/var/lib/python-support/python2.6/django/core/management/__init__.py",
> line 340, in execute_manager
> utility.execute()
> File
> "/var/lib/python-support/python2.6/django/core/management/__init__.py",
> line 295, in execute
> self.fetch_command(subcommand).run_from_argv(self.argv)
> File
> "/var/lib/python-support/python2.6/django/core/management/base.py", line
> 192, in run_from_argv
> self.execute(*args, **options.__dict__)
> File
> "/var/lib/python-support/python2.6/django/core/management/base.py", line
> 219, in execute
> output = self.handle(*args, **options)
> File
> "/var/lib/python-support/python2.6/django/core/management/base.py", line
> 348, in handle
> return self.handle_noargs(**options)
> File
> "/var/lib/python-support/python2.6/django/core/management/commands/syncdb.py",
> line 152, in handle_noargs
> call_command('loaddata', 'initial_data', verbosity=verbosity)
> File
> "/var/lib/python-support/python2.6/django/core/management/__init__.py",
> line 158, in call_command
> return klass.execute(*args, **options)
> File
> "/var/lib/python-support/python2.6/django/core/management/base.py", line
> 219, in execute
> output = self.handle(*args, **options)
> File
> "/var/lib/python-support/python2.6/django/core/management/commands/loaddata.py",
> line 161, in handle
> cursor.execute(line)
> File "/var/lib/python-support/python2.6/django/db/backends/util.py",
> line 19, in execute
> return self.cursor.execute(sql, params)
> psycopg2.ProgrammingError: column "id" does not exist
> LINE 1: ...LECT setval('"venue_member_id_seq"', coalesce(max("id"),
> 1),...
> }}}
>
> The problem seems to be that VenueMember names its pk "id", but gives it
> a db_column='venue_member_id' argument, as follows:
>
> {{{
> class VenueMember(_Model):
> id = models.AutoField(db_column='venue_member_id', primary_key=True)
> venue = models.ForeignKey(Venue)
> member = models.ForeignKey(Member)
> role = models.ForeignKey(Role, null=True, blank=True)
> dates = models.ManyToManyField(Date, blank=True, null=True)
> }}}
>
> This model is referenced in my Venue model in a
> ManyToManyField(through='VenueMember'):
>
> {{{
> class Venue(_Model):
> # [... snip fields ...]
> member_set = models.ManyToManyField('Member',
> through='VenueMember',
> blank=True)
>
> }}}
>
> When the database gets created, it creates a sequence named
> 'venue_member_venue_member_id_seq' on a column named 'venue_member_id',
> but syncdb wants to access it via 'venue_member_id_seq', using the
> column name 'id'.
>
> ./manage.py flush yields the following similar error:
>
> {{{
> Error: Database docsouth_gtts couldn't be flushed. Possible reasons:
> * The database isn't running or isn't configured correctly.
> * At least one of the expected database tables doesn't exist.
> * The SQL was invalid.
> Hint: Look at the output of 'django-admin.py sqlflush'. That's the
> SQL this command wasn't able to run.
> The full error: relation "venue_member_id_seq" does not exist
> }}}
>
> Am I doing something wrong, or should I report a bug?
>
> Cheers,
> Cliff
>
This seems to be closely related to ticket #10881
(db.backends.postgresql.operations.sequence_reset_sql and M2M fields
with non-integer PKs). In fact, the bug can be seen in the code shown
on the ticket description, though it's a different bug.
My initial thought was to make the loop beginning at line 123
(http://code.djangoproject.com/browser/django/trunk/django/db/backends/postgresql/operations.py#L123)
smarter by changing:
style.SQL_FIELD(qn('%s_id_seq' % f.m2m_db_table()))
to:
style.SQL_FIELD(qn('%s_%s_id_seq' % (f.m2m_db_table(),
f.rel.through_model._meta.pk.column)))
and so on, but it occurs to me that if through=MyModel is set on the
ManyToMany, the sequence on MyModel will already be handled by the loop
at line 112. I think I can code up a patch that will fix #10881 and my
problem above in one fell swoop, with the caveat that in order for a
ManyToManyField to function properly with a non-integer primary key, it
will have to be defined as a model, and passed in explicitly with the
through=MyModel syntax.
Patch forthcoming.
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