django-multiforeignkey

Django ForeignKey that links to one of several specified models:

class Comment(models.Model):
        user = models.ForeignKey(User)
        text = models.TextField()

        # users may leave comments for blog posts, articles or votings
        object = MultiForeignKey(Post, Article, Voting)

Unlike GenericForeignKey, the field uses native database foreign keys and provides maximum speed and reliability.

WARNING

This is a preliminary alpha version which most probably doesn’t fully work as advertised. I had to publish it unfinished because I had to use it in my project.

Installation

pip install django-multiforeignkey

Usage

Add multiforeignkey to INSTALLED_APPS:

# settings.py

INSTALLED_APPS = [
        ...
        'multiforeignkey',
]

Add a field to your models:

# comments/models.py

from multiforeignkey.models import MultiForeignKey

class Comment(models.Model):
        user = models.ForeignKey(User)
        text = models.TextField()

        # users may leave comments for blog posts, articles or votings
        object = MultiForeignKey(Post, Article, Voting)

Create the corresponding database tables:

./manage.py makemigrations && ./manage.py migrate

Use the new field as if it were a real database field:

comment = Comment.objects.filter(object=post)
assert comment.object is post
comment.object = voting
assert comment.object is voting
comment.save()

or use specific subfields:

comment = Comment.objects.filter(post=post)
assert comment.post is post
assert comment.article is None
assert comment.voting is None
comment.voting = voting
assert comment.post is None
assert comment.article is None
assert comment.voting is voting
comment.save()