Filtering Django ModelViewSet List From Url Parameter

Question

Hi I have a model like:

class Appointment(models.Model):
    hospital = models.ForeignKey(Hospital, on_delete=models.CASCADE)
    patient = models.ForeignKey(Patient, on_delete=models.CASCADE)

My View looks like:

class AppointmentViewSet(viewsets.ModelViewSet):
    queryset = Appointment.objects.all()
    serializer_class = AppointmentSerializer

In my urls:

router.register(r'appointments', AppointmentViewSet)

Now I want to filter the list of appointments by some patient id. This id should be given by the requester through url. I'm thinking about using kwargs to catch it. But I have no idea how to do it. I know I have to override the list method.

def list(self, request, *args, **kwargs):
    # what do I write here? so that the queryset would be filtered by patient id sent through the url? 

How do I customize the url and/or the view to accommodate the patient id parameter? I just want to modify the list request, all other actions(create, details, destroy) should be handled by the modelviewset's default behavior.

Thanks.

Answer 1

Here is how I ended up doing it:

I've added an url entry like this:

url(r'appointments/ofpatient/(?P<patient>\d+)', AppointmentViewSet.as_view({'get': 'list'})),

Which I can call from the browser as:

http://localhost:8000/appointments/ofpatient/6

and in view:

def list(self, request, patient=None):
    if patient:
        patient = Patient.active.filter(id=patient)
        appts = Appointment.active.order_by('appt_time').filter(patient=patient)
        serializer = self.get_serializer(appts, many=True)
        return Response(serializer.data)
    else:
        appts = Appointment.active.order_by('appt_time')
        serializer = self.get_serializer(appts, many=True)
        return Response(serializer.data)

In this way, the /appointments url is also preserved.

Answer 2

You can define a custom method to handle the routing for the url with the patient id:

from rest_framework.decorators import list_route
rom rest_framework.response import Response

class AppointmentViewSet(viewsets.ModelViewSet):
    ...

    @list_route()
    def patient_appointments(self, request, id=None):
        serializer = self.get_serializer(queryset.filter(patient_id=id), many=True)
        return Response(serializer.data)

The list_route decorator marks your method as requiring routing.

Update:

You can manually register the url as:

url(r'^(?P<id>[0-9]+)/appointments/$', AppointmentViewSet.as_view({'get': 'patient_appointments'}), name='patient-appointments')