Django Serializer Passing a arguments into model function - django

Question

New to Django and DRF, I have a method in the model properties which accept arguments. I have managed to call it successful though a serializer class with default paramenters and getting a JSON response. My problem is I can't pass argument to that function named balance. I have successful pass my argument from view to serializer class but from serializer to model that where I have failed. I thought will be appreciated.
model.py
class Item(models.Model):
entered_by = models.ForeignKey(User, on_delete=models.PROTECT)
name = models.CharField(max_length=50, blank=True)
#property
def balance(self, stock_type='Retail'):
stock = Stock.objects.filter(item=self, type=stock_type, status='InStock').aggregate(models.Sum('quantity')).get('quantity__sum')
return stock or 0
views.py
def getItemInfo(request):
if request.is_ajax and request.method == "GET":
id = request.GET.get("item_id", None)
sell_type = request.GET.get("sell_type", None)
item = Item.objects.get(id=id)
if item:
serializer = ItemSerializer(item, context={'sell_type':sell_type})
return JsonResponse(serializer.data, status = 200, safe=False)
else:
return JsonResponse({"data":False}, status = 400)
serializer.py
from rest_framework import serializers
from .models import Item
class ItemSerializer(serializers.ModelSerializer):
balance = serializers.SerializerMethodField()
class Meta:
model = Item
fields = ('entered_by', 'name', 'balance', 'sell_mode')
def get_balance(self, object):
sell_type = self.context.get("sell_type")
if sell_type:
return object.balance(sell_type)
return object.balance
The error I'm getting
'int' object is not callable

Answer 1

#property couldn't be called. So I made member variable and setter (with calculation) methods in Item model, then make sure setter method will be called in get_balance serializer method, just before returning balance.
Django ORM model itself is just a class; you can do anything class could, not just only linking with ORM.
My Code:
models.py
from django.db import models
from django.contrib.auth.models import User
class Item(models.Model):
entered_by = models.ForeignKey(User, on_delete=models.PROTECT)
name = models.CharField(max_length=50, blank=True)
_balance = 0
def calculate_balance(self, stock_type='Retail'):
stock = Stock.objects.filter(item=self, type=stock_type, status='InStock').aggregate(
models.Sum('quantity')).get('quantity__sum')
self._balance = stock or 0
#property
def balance(self):
return self._balance
serializer.py
from django.contrib.auth.models import User
from rest_framework import serializers
from .models import Item
class ItemSerializer(serializers.ModelSerializer):
balance = serializers.SerializerMethodField()
class Meta:
model = Item
fields = ('entered_by', 'name', 'balance')
def get_balance(self, object):
sell_type = self.context.get("sell_type")
if sell_type:
object.calculate_balance(sell_type)
return object.balance
views.py
from .models import Item
from .serializer import ItemSerializer
from django.http.response import JsonResponse
def getItemInfo(request):
if request.is_ajax and request.method == "GET":
id = request.GET.get("item_id", None)
if id is None:
return JsonResponse({"data": False}, status=400)
sell_type = request.GET.get("sell_type", None)
try:
item = Item.objects.get(id=id)
serializer = ItemSerializer(item, context={'sell_type': sell_type})
return JsonResponse(serializer.data, status=200, safe=False)
except Item.DoesNotExist:
return JsonResponse({"data": False}, status=400)