Django Rest Framework unique field constraint on array - django

Question

So, I'm trying to make an endpoint where I insert a list of objects.
My issue is the behavior and response when inserting duplicates.
What I want to accomplish is to:
Send the duplicate lead external_id(s) in the error response
Insert any other non duplicated object
I'm pretty sure this logic (for the response and behavior) could be accomplished in the modifying the serializer.is_valid() method... but before doing that, I wanted to know if anyone had experience with this kind of request.. Maybe there is a "clean" way to do this while keeping the unique validation in the model.
Data on OK response:
[
{
"external_id": "1",
"phone_number": "1234567890"
}
]
Data for a FAIL request (1 is dup, but 2 should be inserted. Expecting a response like "external_id" : "id 1 is duplicated"):
[
{
"external_id": "1",
"phone_number": "1234567890"
},
{
"external_id": "2",
"phone_number": "2234567890"
}
]
models.py
class Lead(models.Model):
external_id = models.CharField(max_length=20, unique=True)
phone_number = models.CharField(max_length=50)
serializers.py
class LeadSerializer(serializers.ModelSerializer):
class Meta:
model = Lead
fields = '__all__'
def create(self, validated_data):
lead = Lead.objects.create(**validated_data)
log.info(f"Lead created: {lead.import_queue_id}")
return lead
views.py
class LeadView(APIView):
authentication_classes = [TokenAuthentication]
permission_classes = [IsAuthenticated]
#extend_schema(description="Insert campaign data", request=LeadSerializer(many=True), responses=None, tags=["Leads"])
def post(self, request):
serializer = LeadSerializer(data=request.data, many=True)
valid = serializer.is_valid()
if serializer.is_valid():
serializer.save()
return Response({"status": "success", "data": serializer.data}, status=status.HTTP_200_OK)
else:
return Response({"status": "error", "data": serializer.errors}, status=status.HTTP_400_BAD_REQUEST)

Answer 1

You can customize the behaviour of list of object through list_serializer_class option in meta class. Like this:
class LeadListSerializer(serializers.ListSerializer):
def validate(self, data):
items = list(map(lambda x: x['phone_number'], data))
if len(set(items)) == len(items)):
return super().validate(data)
raise ValidationError()
class LeadSerializer(serializers.ModelSerializer):
class Meta:
model = Lead
fields = '__all__'
list_serializer_class = LeadListSerializer