ContentTypes and GenericForeignKeys

Content Types and GenericForeignKeys are for relationships where the model on one end is not defined by the model’s schema.

If you’re using GenericForeignKeys in django, you can use a GenericForeignKeyField in Tastypie.


Here’s an example model with a GenericForeignKey taken from the Django docs:

from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import generic

class TaggedItem(models.Model):
    tag = models.SlugField()
    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField()
    content_object = generic.GenericForeignKey('content_type', 'object_id')

    def __unicode__(self):
        return self.tag

A simple ModelResource for this model might look like this:

from tastypie.contrib.contenttypes.fields import GenericForeignKeyField
from tastypie.resources import ModelResource

from .models import Note, Quote, TaggedItem

class QuoteResource(ModelResource):

    class Meta:
        resource_name = 'quotes'
        queryset = Quote.objects.all()

class NoteResource(ModelResource):

    class Meta:
        resource_name = 'notes'
        queryset = Note.objects.all()

class TaggedItemResource(ModelResource):
    content_object = GenericForeignKeyField({
        Note: NoteResource,
        Quote: QuoteResource
    }, 'content_object')

    class Meta:
        resource_name = 'tagged_items'
        queryset = TaggedItem.objects.all()

A ModelResource that is to be used as a relation to a GenericForeignKeyField must also be registered to the Api instance defined in your URLconf in order to provide a reverse uri for lookups.

Like ToOneField, you must add your GenericForeignKey attribute to your ModelResource definition. It will not be added automatically like most other field or attribute types. When you define it, you must also define the other models and match them to their resources in a dictionary, and pass that as the first argument, the second argument is the name of the attribute on the model that holds the GenericForeignKey.