Build request URL to filter Django queryset multiple times by the same field

Question

I want to filter Django queryset by the same field multiple times using Q to include/exclude records with specific value in this field.

I'll use sample model to illustrate my case. Say I have a Record model with field status. This field can be one of three states A, B, C.

class Record(models.Model):
    STATUS_A = 'A'
    STATUS_B = 'B'
    STATUS_C = 'C'

    SOME_STATUSES = (
        (STATUS_A, 'Something A'),
        (STATUS_B, 'Something B'),
        (STATUS_C, 'Something C'),
    )

    status = models.CharField(
    max_length=1,
    choices= SOME_STATUSES,
    default= STATUS_A,
    )

I have a DRF ViewSet that's responsible for returning filtered queryset of Record objects.

Right now I'm filtering query set by a single status, so my URL looks something like:

.../?status=A
.../?status=B
.../?status=C

But say I want to filter queryset by multiple statuses: Return all records with status A and B. Or instead I want to return all the records except those with status C. I'm not sure how to build URL in those cases. I know that duplicating parameters in URL is a very bad practice:

.../?status=A&status=B

How does one request A AND B or NOT C?

The remaining part of the question how to handle those multiple values is unclear probably because I don't understand how to build such a query in the first place.

Can you share the `ViewSet` code? DRF has some support for membership checks. — Willem Van Onsem, Aug 30 '18 at 11:02
@WillemVanOnsem it's rather vast, because the actual ViewSet filters a query with several different params and I'm using several Mixins to keep things in order. I'll try to minimise it to fit a question and upload it later today. But mainly my question is how to build such url's. — Stan Reduta, Aug 30 '18 at 11:05
I think you should send an `array` on the querystring and then filter in the backend. `.../?status=[A,B,C]`. Also try to use `django-filters` — Marcos Schroh, Aug 30 '18 at 11:06
`/?status_must=A,B&status_mustnot=C` Is this your expected url? — JPG, Aug 30 '18 at 11:11

score 1 · Accepted Answer · edited Sep 20 '18 at 04:53

By writing CustomDjangoFilter you can achieve this.

Sample Code

URL examples and Usage

URL  : localhost:8000/records/?status_include=A,B
URL  : localhost:8000/records/?status_exclude=A
URL  : localhost:8000/records/?status_include=A,B,C&status_exclude=D,E,F

Code Snippet

views.py

from django_filters.rest_framework import DjangoFilterBackend
from .filters import CustomRecordFilter

class RecordViewSet(viewsets.ModelViewSet):
    queryset = Record.objects.all()
    serializer_class = RecordSerializer

    # django-filter-backend and custom-filter-class
    filter_backends = (DjangoFilterBackend, )
    filter_class = CustomRecordFilter

filters.py

import django_filters

class CustomRecordFilter(django_filters.FilterSet):
    status_exclude = django_filters.CharFilter(field_name='status', method='filter_status_exclude')
    status_include = django_filters.CharFilter(field_name='status', method='filter_status_include')

def filter_status_include(self, queryset, name, value):
    if not value:
        return queryset
    values = ''.join(value.split(' ')).split(',')
    queryset = queryset.filter(status__in=values)
    return queryset

def filter_status_exclude(self, queryset, name, value):
    if not value:
        return queryset
    values = ''.join(value.split(' ')).split(',')

    # exclude status
    queryset = queryset.exclude(status__in=values)
    return queryset

class Meta:
    model = UserRoleGroup
    fields = ('status', 'status_include', 'status_exclude')

Build request URL to filter Django queryset multiple times by the same field

1 Answers1