On Mon, Aug 8, 2011 at 3:06 PM, Chintan Tank <tankchin...@gmail.com> wrote: > (sorry for duplicate I have already posted on stackoverflow.com > > http://goo.gl/I7Jj6 ) > > I need to perform a datamigration of a model Answer in app Question. > In that script there is a dependency such that I need to create an > instance of a model Chapter which is in the app Journal. So, I coded > it as follows: > > def forwards(self, orm): > for answer_object in orm.Answer.objects.all(): > > #This Works. > blog, is_created = > orm['blog.Post'].objects.get_or_create(title=answer_object.answer[: > 100]) > blog.save() > > #This DOES NOT work > chapter, is_created = > orm['journal.Chapter'].objects.get_or_create(content_object=blog) > chapter.save() > #cleanup task, not relevant to this question below > answer_object.chapter_ptr = chapter > answer_object.save() > > > > But as expected this throws an error on " > orm['journal.Chapter'].objects.get_or_create(content_object=blog)" > saying that > django.core.exceptions.FieldError: Cannot resolve > keyword 'content_object' into field. > > This is presumably due to content_object being a GenericForeignKey so > some operations are not allowed. But I also tried other alternatives > for creating the "chapter" object like, > > chapter = orm['journal.Chapter'](content_object=blog) > ERROR > TypeError: 'content_object' is an invalid keyword argument for > this function > > and > > chapter = orm.journal.Chapter(content_object=blog) > ERROR > AttributeError: The model 'journal' from the app 'questions' > is not available in this migration. (Did you use orm.ModelName, not > orm['app.ModelName']?) > > So since my earlier approach was failing I tried a new tact. The model > whose instantiation was failing in my code above i.e. Chapter in the > Journal app, I decided to create a datamigration for that instead. I > also made sure to --freeze the models I am referring to in the > forwards definition. Now this should have been straight forward, I > would think. I have my forward code as follows - > > def forwards(self, orm): > > for answer_object in orm['questions.Answer'].objects.all(): > > #Works, AGAIN! > blog, is_created = > orm['blog.Post'].objects.get_or_create(title=answer_object.answer[: > 100]) > blog.save() > > # DOES NOT WORK, AGAIN! > chapter = orm.Chapter(rank=1, content_object=blog) > chapter.save() > > > I would have thought that now since I am creating instance of a model > (Chapter) which exists in the subject app (Journal) everything should > have worked out. But i am getting the same error > TypeError: > 'content_object' is an invalid keyword argument for this function. > > It fails at the same point, namely, "content_object". I will post > below the model definition if that might help. > > class Chapter(models.Model): > > rank = models.IntegerField() > > content_type = models.ForeignKey(ContentType) > object_id = models.PositiveIntegerField() > content_object = generic.GenericForeignKey() > > Also all the models being touched in these forwards methods, namely - > blog, chapter, questions; are fully defined in the 00n_*.py files > created by South's schemamigration. >
content_object isn't a 'real' field, it is some magic applied to the ORM and your model. The real fields are object_id and content type, so use them directly. Use ContentType.objects.get_for_model() [1] to get the content type. [1] https://docs.djangoproject.com/en/1.3/ref/contrib/contenttypes/#django.contrib.contenttypes.models.ContentTypeManager.get_for_model Cheers Tom -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
