Question

I’m porting a project from Rails to Django with a legacy database. In Rails I had a polymorphic association that allowed me to add a footnote to any row in the database. I’m trying to implement the same thing in the Django app. I found the documentation on Generic Relations and it looks perfect. Unfortunately, I first need to create new fields in my legacy database to hold the ContentType id for the relevant models. I only used the polymorphic association with 2 tables, so all I need are those two corresponding ids from the Django app, but I can’t seem to find the appropriate command for looking up a ContentType id in Django.

Any suggestions are most welcome. I tried searching through previous questions but couldn’t seem to find what I am looking for. Thank you very much for you time and help.

Answer 1

from the docs

you can do:

>>> b = Bookmark.objects.get(url='https://www.djangoproject.com/')
>>> bookmark_type = ContentType.objects.get_for_model(b)
>>> TaggedItem.objects.filter(content_type__pk=bookmark_type.id,
...                           object_id=b.id)

so just instantiate an instance of your model and then do ContentType.objects.get_for_model(<instance>).id

I think there’s a way to pass just the model name, too… let me know if that would work better and I’ll try to find it; I’ve used it in the past.