Filtering django rest framework query set using a custom filter backend

Question

I'm having problems with filtering the query set. Here is a simplified data model:

Entry
- id
- broadcast_groups

User
- id
- groups

So an entry can be broadcasted (shared) in a group. I have a GET /entries/ endpoint that returns entry objects.

I want to filter a query set to return entries that fulfill following requirements:

are not broadcasted in any group OR
are broadcasted in groups the user is member of.

I'm scratching my head how to achieve this. I figured that maybe writing a custom FilterBackend is a good idea. Here is what I have so far:

class CanViewPublicOrGroupMemberEntriesFilterBackend(filters.BaseFilterBackend):

    def filter_queryset(self, request, queryset, view):
        user = request.user
        return queryset.filter(broadcast_groups__in=user.groups.all())

However, this does not yield results that I am expecting. What would be a filter() syntax to achieve such filtering? Or maybe I'm approaching the problem from the wrong side?

Sardorbek Imomaliev · Accepted Answer · 2017-11-06 17:03:35Z

2

You are looking for Q objects https://docs.djangoproject.com/en/1.11/topics/db/queries/#complex-lookups-with-q-objects

class CanViewPublicOrGroupMemberEntriesFilterBackend(filters.BaseFilterBackend):
    def filter_queryset(self, request, queryset, view):
        user = request.user
        return queryset.filter(
            Q(broadcast_groups__in=user.groups.all()) |
            Q(broadcast_groups__isnull=True)
        )

answered Nov 6, 2017 at 17:03

Sardorbek Imomaliev

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1 Comment

Rafał Sroka Over a year ago

This is so simple!

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