device validation by serial - DeviceException

apps/pos_device/web/api/v1/serilaizers/device.py

@@ -3,6 +3,7 @@ from rest_framework.serializers import ModelSerializer
 from apps.authentication.api.v1.serializers.serializer import BankAccountSerializer
 from apps.pos_device import exceptions as pos_exceptions
 from apps.pos_device import models as pos_models
+from apps.pos_device.exceptions import DeviceException
 from apps.pos_device.web.api.v1.serilaizers import client as client_serializer
 from apps.product.web.api.v1.serializers.quota_distribution_serializers import QuotaDistributionSerializer
 
@@ -18,6 +19,19 @@ class DeviceSerializer(ModelSerializer):
         model = pos_models.Device
         fields = '__all__'
 
+    def validate(self, attrs):
+        serial = attrs['serial']
+
+        if not self.instance:
+            if self.Meta.model.objects.filter(serial=serial).exists():
+                raise DeviceException("دستگاه یا این شماره سریال از قبل ثبت شده است.", status_code=403)  # noqa
+
+        if self.instance:
+            if serial != self.instance.serial and self.Meta.model.objects.filter(serial=serial).exists():
+                raise DeviceException("دستگاهی با این شماره سریال وجود دارد.", status_code=403)  # noqa
+
+        return attrs
+
     def to_representation(self, instance):
         """ custom output of serializer """
         representation = super().to_representation(instance)