[Answered ]-Related set of GenericForeignKey in Django


Given a user, you want to query for every “subscribable” (e.g. Netflix or National Geographic) that the user has subscribed to. If I understood the question correctly, then this is all you need:

subscribed_tos = [subscription.subscribed_to for subscription
    in user.subscription_set.all()]

No, it’s not possible to do it in a single database query. This should be obvious if you know how the contenttypes system works and are aware the queries are being implemented via SQL.

However, if you only want a user’s subscriptions to instances of one model class (say, all of a user’s magazine subscriptions), you can do it in one query. Just add a GenericRelation to that model, and you can query through it:

class Subscribable(model.Model):
    subscriptions = generic.GenericRelation(Subscription)

    class Meta:
        abstract = True

class Magazine(Subscribable):

subscribed_magazines = Magazine.objects.filter(subscriptions__user__exact=user)

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