2018-06-23

Use django-filter to add filter for REST api

For a REST list api, filtering and sorting is the basic requirements. Using django-filter, we can add these functions with only a few lines of codes.

For example, if we have a model as follows,

class Product(models.Model):
    name = models.CharField(max_length=100)
    created_at = models.DatetimeField()

We will write relative serializer and view.

class ProductSerializer(serializers.ModelSerializer):
    class Meta:
        fields = '__all__'

class ProductListView(generics.ListView):
    queryset = Product.objects.all()
    serializer_class = ProductSerializer

If we don’t use django-filter, we can override ProductListview’s get_queryset to implement filter. For example, to filter by name:

def get_queryset(self):
    queryset = Product.objects.all()
    name = self.request.query_params.get('name', None)
    if name is not None:
        queryset = queryset.filter(name=name)
    return queryset

With django-filter, the code can be even simpler. We can just code like configuration to implement more advanced filters. First, we install it with pip install django-filter. Then, we add a filter class in our views.

class ProductFilter(django_filters.FilterSet):
    sort = django_filters.OrderingFilter(fields=('created_at',))

    class Meta:
        model = Product
        fields = ['name',]

Then modify our ProductListView by adding following two lines

filter_backends = (DjangoFilterBackend,)
filter_class = ProductFilter

Now filter by name and sorting by created_at are both implemented. If the original list url is /products/, to search by name, the url is /products/?name=iPhone; to order by created_at desc, the url is /products/?sort=-created_at.

Django-filter can implement more advanced features, e.g, filter by range, fuzzy search. Please refer to Official doc.