Django REST Filtering Tutorial (5 Part Series)
  1. Django REST Filtering Tutorial - Intro (Part I)
  2. Django REST Filtering Tutorial - Filter with Current User (Part II)
  3. Django REST Filtering Tutorial - Filter Against URL (Part III)
  4. Django REST Filtering Tutorial - Filter with Parameters(Part IV)
  5. DRF - Map Filter QuerySet Parameters (Part V)

Entrée

Sometimes we need to map some url parameters to different model fields, due to some restrictions or for backward compability.

Let’s say we’d like to show/filter “customer” instead of “user” in our DRF API.

# httpie
$ http ":8000/authors?customer=3"
# or with curl
# $ curl http://localhost:8000/authors?customer=3

[
    {
        "first_name": "Name3",
        "full_name": "Name3 Surname3",
        "id": 3,
        "last_name": "Surname3",
        "customer": 3
    }
]

Initial Code

For this purpose I will use our Django REST Framework example github repo. You can find updated code on the branch map-filter-params.

Let’s use our basic ArticleViewSet shown below:

# src/articles/views.py
class ArticleViewSet(viewsets.ModelViewSet):
    serializer_class = ArticleSerializer
    queryset = Article.objects.all()
    filter_backends = (
        DjangoFilterBackend,
        OrderingFilter,
        SearchFilter,
    )
    filterset_fields = ("id", "title", "regions", "regions__code")
    search_fields = ("id", "title", "regions__name", "regions__code")
    ordering_fields = ("title",)
    ordering = "title"

In this view, as you may see, we filter with id, title, regions, regions__code.

Custom FilterSet

Mapping a filter field to different model field is quite simple: just provide field_name param to related filter.

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# src/articles/filters.py
from django_filters import rest_framework as filters

from src.articles.models import Article


class ArticleFilterSet(filters.FilterSet):
    subject = filters.CharFilter(field_name="title", lookup_expr="exact")

    class Meta:
        model = Article
        fields = ("id", "subject", "regions", "regions__code")

Then you can use this custom FilterSet in the view like below:

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class ArticleViewSet(viewsets.ModelViewSet):
    serializer_class = ArticleSerializer
    queryset = Article.objects.all()
    filter_backends = (
        DjangoFilterBackend,
        OrderingFilter,
        SearchFilter,
    )
    filterset_class = ArticleFilterSet
    search_fields = ("id", "title", "regions__name", "regions__code")
    ordering_fields = ("title",)
    ordering = "title"

All done!