Model Instances not valid when used as arguments for creating another object

[daryl@…]

I'm having trouble with creating new objects in a datamigration.

When using object instances from the South orm, e.g. content_type_instance = ormcontenttypes.ContentType?.objects.get(ct_kwargs)

to create another object:

publishing_kwargs = {

'site': site if isinstance(site, Site) else Site.objects.get(id=site.id),
'publishing_type': publishing_type_instance,
'start': start,
'content_type': content_type_instance,
'object_id': content_object.id, }

publishing = orm.Publishing(publishing_kwargs)

I get a ValueError?:

Cannot assign "<ContentType: ContentType object>": "Publishing.content_type" must be a "ContentType?" instance.

See also:

​http://stackoverflow.com/questions/6211027/south-data-migration-instance-error-when-using-south-freeze-orm/6215957#6215957

​http://dpaste.com/hold/549891/

[daryl@…]

datamigration file

[andrew]

This is because the south ORM classes of models are _not the same_ as the main Django classes for your models - they won't compare equal, and you can't feed instances of one type into a ForeignKey? of another type.

Unfortunately, knowing which kind a ForeignKey? is can sometimes be tricky. Have you tried both with and without the orm version of ContentType??

[daryl@…]

updated data migration with hopeful fixes

[daryl@…]

print debug output of migration

[daryl@…]

Thanks @andrew, I've reattached an updated version of the file whereas I attempt to get the 'native' instances for use in creating new objects.

With the 'Publishing' object that I'm trying to create, you'll notice at the bottom that I try the 3 possible notations for creating objects, two of them via the south orm, and the third via native django.

Each of them returns the instance error, however, curiously, complaining about different objects, i.e. sometimes about the content_type, and sometimes about the 'site'.

I've included the output from the print statements found in the migration.

I had a 'feeling' that orm.ContentType? != ContentType? -- yet, this issue seems to be baffling.

[daryl@…]

Uhhh, nevermind. Programmer error :)

[brandon.ivey@…]

Replying to daryl@…:

Uhhh, nevermind. Programmer error :)

Daryl, what was the error, and how did you get around it? Having similar problems with migrations involving contenttypes.