Fix bug when using gcm serializer as a nested serializer.

When the serializer is nested the unique validator on registration_id
does not behave correctly.  This is a known issue with DRF
see: encode/django-rest-framework#2403

Added missing allow_null to device_id field

Fixes jazzband#270

push_notifications/api/rest_framework.py

@@ -2,7 +2,6 @@
 
 from rest_framework import permissions
 from rest_framework.serializers import ModelSerializer, ValidationError
-from rest_framework.validators import UniqueValidator
 from rest_framework.viewsets import ModelViewSet
 from rest_framework.fields import IntegerField
 
@@ -22,7 +21,7 @@ def to_internal_value(self, data):
 		# validate hex string and convert it to the unsigned
 		# integer representation for internal use
 		try:
-			data = int(data, 16)
+			data = int(data, 16) if type(data) != int else data
 		except ValueError:
 			raise ValidationError("Device ID is not a valid hex number")
 		return super(HexIntegerField, self).to_internal_value(data)
@@ -34,7 +33,7 @@ def to_representation(self, value):
 # Serializers
 class DeviceSerializerMixin(ModelSerializer):
 	class Meta:
-		fields = ("name", "registration_id", "device_id", "active", "date_created")
+		fields = ("id", "name", "registration_id", "device_id", "active", "date_created")
 		read_only_fields = ("date_created", )
 
 		# See https://github.com/tomchristie/django-rest-framework/issues/1101
@@ -59,29 +58,33 @@ def validate_registration_id(self, value):
 class GCMDeviceSerializer(ModelSerializer):
 	device_id = HexIntegerField(
 		help_text="ANDROID_ID / TelephonyManager.getDeviceId() (e.g: 0x01)",
-		style={'input_type': 'text'},
-		required=False
+		style={"input_type": "text"},
+		required=False,
+		allow_null=True
 	)
 
 	class Meta(DeviceSerializerMixin.Meta):
 		model = GCMDevice
 
-		extra_kwargs = {
-			# Work around an issue with validating the uniqueness of
-			# registration ids of up to 4k
-			'registration_id': {
-				'validators': [
-					UniqueValidator(queryset=GCMDevice.objects.all())
-				]
-			}
-		}
+		extra_kwargs = {"id": {"read_only": False, "required": False}}
 
 	def validate_device_id(self, value):
 		# device ids are 64 bit unsigned values
 		if value > UNSIGNED_64BIT_INT_MAX_VALUE:
 			raise ValidationError("Device ID is out of range")
 		return value
 
+	def validate(self, attrs):
+		devices = None
+		if self.context["request"].method in ["PUT", "PATCH"]:
+			devices = GCMDevice.objects.filter(registration_id=attrs["registration_id"]) \
+				.exclude(id=attrs["id"])
+		elif self.context["request"].method == "POST":
+			devices = GCMDevice.objects.filter(registration_id=attrs["registration_id"])
+		if devices:
+			raise ValidationError("Registration ID must be unique")
+		return attrs
+
 
 # Permissions
 class IsOwner(permissions.BasePermission):