Return results from multiple models with Django REST Framework

Question

I have three models — articles, authors and tweets. I'm ultimately needing to use Django REST Framework to construct a feed that aggregates all the objects using the Article and Tweet models into one reverse chronological feed.

Any idea how I'd do that? I get the feeling I need to create a new serializer, but I'm really not sure.

Thanks!

Edit: Here's what I've done thus far.

app/serializers.py:

class TimelineSerializer(serializers.Serializer):
    pk = serializers.Field()
    title = serializers.CharField()
    author = serializers.RelatedField()
    pub_date = serializers.DateTimeField()

app/views.py:

class TimelineViewSet(viewsets.ModelViewSet):
    """
    API endpoint that lists all tweet/article objects in rev-chrono.
    """
    queryset = itertools.chain(Tweet.objects.all(), Article.objects.all())
    serializer_class = TimelineSerializer

Is your question about how to merge the two timelines of different objects or how to use DRF to output the already-merged timeline? — David Jones - iPushPull
– David Jones - iPushPull, Commented Sep 9, 2013 at 16:54
Probably both, on some level ('Fraid I'm a bit of a Django neophyte...). I'll update the code with what I have in a minute, but I've currently created a new view that uses itertools.chain() to create a queryset combining Tweet.objects.all() and Article.objects.all() and gives it to a new serializer that lists the fields common to the two models. Am I anywhere near on the right path? — aendra
– aendra, Commented Sep 9, 2013 at 17:10
You can use this - github.com/Axiologue/DjangoRestMultipleModels. — Shubham
– Shubham, Commented Sep 1, 2015 at 11:13

David Jones - iPushPull · Accepted Answer · 2013-09-09 17:46:04Z

27

It looks pretty close to me. I haven't used ViewSets in DRF personally, but I think if you change your code to this you should get somewhere (sorry - not tested either of these):

class TimelineViewSet(viewsets.ModelViewSet):
    """
    API endpoint that lists all tweet/article objects in rev-chrono.
    """
    def list(self, request):
        queryset = list(itertools.chain(Tweet.objects.all(), Article.objects.all()))
        serializer = TimelineSerializer(queryset, many=True)
        return Response(serializer.data)

If you're not wedded to using a ViewSet then a generics.ListAPIView would be a little simpler:

class TimeLineList(generics.ListAPIView):
    serializer_class = TimeLineSerializer

    def get_queryset(self):
        return list(itertools.chain(Tweet.objects.all(), Article.objects.all()))

Note you have to convert the output of chain to a list for this to work.

edited Sep 9, 2013 at 17:46

answered Sep 9, 2013 at 17:35

David Jones - iPushPull

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4 Comments

aendra Over a year ago

I tried the second route, and am getting the following error: "base_name argument not specified, and could not automatically determine the name from the viewset, as it does not have a .model or .queryset attribute." If I replace the "get_queryset" stanza with queryset = list(itertools.chain(Tweet.objects.all(), Article.objects.all())), nothing happens and the whole thing hangs. Any idea what I might be doing wrong?

aendra Over a year ago

Woo, totally got the first variant working. Additional notes for anyone finding this: 1. You need from rest_framework.response import Response in views.py. 2. When registering the router in site/urls.py, I needed to specify base_name like so: router.register(r'timeline', views.TimelineViewSet, 'timeline').

aendra Over a year ago

Another note — the fields used in the serializer must be present in both models fed to itertools.chain(), merely setting "required=False" for the unique field in the serializer won't do anything.

Amistad Over a year ago

you should ideally post the comment as an answer or add the edit to the question so that it helps someone else

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