Query on User related Object in Django

Question

In my Application I am trying to query a field which in depth requires a reverse lookup. Let me explain by Models

Models.py

class User(AbstractUser):
    is_employee = models.BooleanField(default=False)
    is_client = models.BooleanField(default=False)

class Client(models.Model):
   
    user = models.OneToOneField(User, on_delete=models.CASCADE, primary_key=True)
    client_name = models.CharField(max_length=500, default=0)


class MaterialRequest(models.Model):

    owner = models.ForeignKey(User, on_delete=models.CASCADE)
    flows = models.ManyToManyField(MaterialRequestFlow)
    is_allocated = models.BooleanField(default=False)

class Allotment(models.Model):

    transaction_no = models.IntegerField(default=0)
    dispatch_date = models.DateTimeField(default=datetime.now)
    send_from_warehouse = models.ForeignKey(Warehouse, on_delete=models.CASCADE)
    sales_order = models.ForeignKey(MaterialRequest, on_delete=models.CASCADE)

Now I want to query Allotment which are created by a particular Client. In the frontend I have a dropdown of Clients which sends the id of the Client

Here's my function for this:

Views.py

class AllotmentReport(APIView):
    permission_classes = (permissions.IsAuthenticated,)

    def get(self, request, *args, **kwargs):
        cname = self.kwargs['cname']
        if self.kwargs['cname']:
            items = Allotment.objects.filter(sales_order__owner??? = cname).order_by('-id')    #Need Help Here
        else:
            items = Allotment.objects.all().order_by('-id')
            
        serializer = AReportSerializer(items, many=True)

        return Response(serializer.data, status=status.HTTP_201_CREATED)

Also I'd like to know If there is a better alternative to do that

What value you are providing by cname?

Pruthvi Barot
– Pruthvi Barot

2020-07-27 11:46:31 +00:00
Commented Jul 27, 2020 at 11:46 — Pruthvi Barot
– Pruthvi Barot, Commented Jul 27, 2020 at 11:46
'id' of 'Client` Model

Rahul Sharma
– Rahul Sharma

2020-07-27 11:47:25 +00:00
Commented Jul 27, 2020 at 11:47 — Rahul Sharma
– Rahul Sharma, Commented Jul 27, 2020 at 11:47

Pruthvi Barot · Accepted Answer · 2020-07-27 12:00:31Z

1

def get(self, request, *args, **kwargs):
        cname = self.kwargs['cname']
        if self.kwargs['cname']:
            client = Client.objects.get(id=cname)
            items = Allotment.objects.filter(sales_order__owner=client.user).order_by('-id')
        else:
            items = Allotment.objects.all().order_by('-id')
            
        serializer = AReportSerializer(items, many=True)

    return Response(serializer.data, status=status.HTTP_201_CREATED)

edited Jul 27, 2020 at 12:00

answered Jul 27, 2020 at 11:49

Pruthvi Barot

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4 Comments

Rahul Sharma Over a year ago

I am getting NameError: name 'client__user' is not defined

Pruthvi Barot Over a year ago

oh my bad. Updated the answer

Rahul Sharma Over a year ago

One more help please ? I am getting the data in 5.13 s and size is 45.35 KB, basically 100 objects and that even without using depth. Can I speed it up ?

Pruthvi Barot Over a year ago

One solution is to take created_by field in Allotment, ForeignKey of user, and update after creating a record. Then no need for a nested filter.

Vincent · Accepted Answer · 2020-07-27 11:53:24Z

0

You can get the user through the client and then get the MaterialRequest owners by filtering on those users.

material_request_owners = []

try:
    user = Client.objects.get(id=cname).user
    material_request_owners = MaterialRequest.objects.filter(owner=user)     
except (AttributeError, Client.DoesNotExist():
    return # error message


if len(material_request_owners) > 0:     
    items = Allotment.objects.filter(sales_order=material_request_owners).order_by('-id')
else:
    items = Allotment.objects.all().order_by('-id')

answered Jul 27, 2020 at 11:53

Vincent

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