def post(self, request, *args, **kwargs): serializer = self.get_serializer(data=request.data) serializer.is_valid(raise_exception=True) payment = Payment() try: payment.contract = Contract.objects.get( id=serializer.data['contract']) except: return Response("Contract don't exists.") payment.payment_amount = serializer.data['payment_amount'] payment.save() headers = self.get_success_headers(serializer.data) return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)