How to use Query Strings for filtering Querysets in Django?

Question

I created my "API" using REST framework, now I am trying to do filtering for it.

This is how my models.py looks like:

class Airline(models.Model):
    name = models.TextField()

class Workspace(models.Model):
    airline = models.ForeignKey(Airline)
    name = models.CharField(max_length=100)

class Passenger(models.Model):
    workspace = models.ForeignKey(Workspace)
    title = models.CharField(max_length=200)

I would like to see "all passengers in particular workspace" or "all passengers in particular airline" etc in my JSON file.

Here is my serializers.py:

class AirlineSerializer(serializers.ModelSerializer):
    class Meta:
        model = Airline


class WorkspaceSerializer(serializers.ModelSerializer):
    class Meta:
        model = Workspace


class PassengerSerializer(serializers.ModelSerializer):
    class Meta:
        model = Passenger

And views.py:

class AirlineList(generics.ListCreateAPIView):
    model = Airline
    serializer_class = AirlineSerializer


class AirlineDetail(generics.RetrieveUpdateDestroyAPIView):
    model = Airline
    serializer_class = AirlineSerializer


class WorkspaceList(generics.ListCreateAPIView):
    model = Workspace
    serializer_class = WorkspaceSerializer


class WorkspaceDetail(generics.RetrieveUpdateDestroyAPIView):
    model = Workspace
    serializer_class = WorkspaceSerializer


class PassengerList(generics.ListCreateAPIView):
    model = Passenger
    serializer_class = PassengerSerializer


class PassengerDetail(generics.RetrieveUpdateDestroyAPIView):
    model = Passenger
    serializer_class = PassengerSerializer

I would like to use Filtering against query parameter but I can't really get it...

The docs are quite straight forward, what you need to do is to implement the get_queryset method in your generics.ListCreateAPIView — Henrik Andersson
– Henrik Andersson, Commented Jan 17, 2014 at 10:20
The example in the docs are, literally, the exact thing you need. Change username for whatever query parameter name you have. — Henrik Andersson
– Henrik Andersson, Commented Jan 17, 2014 at 10:23
Here is another answer for complex filtering in Django rest framework : stackoverflow.com/questions/14258338/… — iankit
– iankit, Commented Feb 19, 2016 at 13:22

Sabito · Accepted Answer · 2021-08-23 06:14:27Z

81

Here is the code:

class PassengerList(generics.ListCreateAPIView):
    model = Passenger
    serializer_class = PassengerSerializer

    # Show all of the PASSENGERS in particular WORKSPACE
    # or all of the PASSENGERS in particular AIRLINE
    def get_queryset(self):
        queryset = Passenger.objects.all()
        workspace = self.request.query_params.get('workspace')
        airline = self.request.query_params.get('airline')

        if workspace:
            queryset = queryset.filter(workspace_id=workspace)
        elif airline:
            queryset = queryset.filter(workspace__airline_id=airline)

        return queryset

edited Aug 23, 2021 at 6:14

Sabito

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answered Jan 17, 2014 at 12:29

knowbody

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3 Comments

Clocker Over a year ago

Note that this approach will work as long as your URLConf is setup with the params set in the traditional ?param1=value&.... See django-rest-framework.org/api-guide/filtering/… for more

Petter Kjelkenes Over a year ago

request.QUERY_PARAMS has been deprecated in favor of request.query_params since version 3.0, and has been fully removed as of version 3.2.

Manjit Kumar Over a year ago

you may want explore this django app for filtering queryset based on query params github.com/manjitkumar/drf-url-filters

Sabito · Accepted Answer · 2021-08-23 06:19:32Z

22

You can get the same functionality out of the box just by using django-filter package as stated in the docs: DjangoFilterBackend

from rest_framework import filters 

class PassengerList(generics.ListCreateAPIView):
    model = Passenger
    serializer_class = PassengerSerializer
    queryset = Passenger.objects.all()
    filter_backends = (filters.DjangoFilterBackend,)
    filter_fields = ('workspace', 'workspace__airline')

In this case you will have to make filtering using workspace=1 or workspace__airline=1.

edited Aug 23, 2021 at 6:19

Sabito

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answered Feb 25, 2016 at 11:48

Gabriel Muj

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1 Comment

Nicolò Gasparini Over a year ago

Please note that from DRF 3.7 they removed the filter, it can still be included by installing django-filter. The documentation link you provided is still valid though

Manjit Kumar · Accepted Answer · 2016-04-09 21:37:50Z

This django app applies filters on the queryset of a view using the incoming query parameters in an clean and elegant way.

Which can be installed with pip as pip install drf-url-filters

Usage Example

validations.py

from filters.schema import base_query_param_schema
from filters.validations import (
    CSVofIntegers,
    IntegerLike,
    DatetimeWithTZ
)

# make a validation schema for players filter query params
players_query_schema = base_query_param_schema.extend(
    {
        "id": IntegerLike(),
        "name": unicode,
        "team_id": CSVofIntegers(),  # /?team_id=1,2,3
        "install_ts": DatetimeWithTZ(),
        "update_ts": DatetimeWithTZ(),
    }
)

views.py

from rest_framework import (
    viewsets,
    filters,
)

from .models import Player, Team
from .serializers import PlayerSerializer, TeamSerializer
from .pagination import ResultSetPagination
from .validations import teams_query_schema, players_query_schema
from filters.mixins import (
    FiltersMixin,
)


class PlayersViewSet(FiltersMixin, viewsets.ModelViewSet):
    """
    This viewset automatically provides `list`, `create`, `retrieve`,
    `update` and `destroy` actions.
    """
    serializer_class = PlayerSerializer
    pagination_class = ResultSetPagination
    filter_backends = (filters.OrderingFilter,)
    ordering_fields = ('id', 'name', 'update_ts')
    ordering = ('id',)

    # add a mapping of query_params to db_columns(queries)
    filter_mappings = {
        'id': 'id',
        'name': 'name__icontains',
        'team_id': 'teams',   # many-to-many relationship
        'install_ts': 'install_ts',
        'update_ts': 'update_ts',
        'update_ts__gte': 'update_ts__gte',
        'update_ts__lte': 'update_ts__lte',
    }

    # add validation on filters
    filter_validation_schema = players_query_schema

    def get_queryset(self):
        """
        Optionally restricts the queryset by filtering against
        query parameters in the URL.
        """
        query_params = self.request.query_params
        queryset = Player.objects.prefetch_related(
            'teams'  # use prefetch_related to minimize db hits.
        ).all()

        # This dict will hold filter kwargs to pass in to Django ORM calls.
        db_filters = {}

        # update filters dict with incoming query params and then pass as
        # **kwargs to queryset.filter()
         db_filters.update(
            self.get_queryset_filters(
                query_params
            )
        )
        return queryset.filter(**db_filters)

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