duplicate Key violation in Django insert doing after Django update

Question

first i update my model instance, after that i tried to insert a new data but showing

"IntegrityError(\'duplicate key value violates unique constraint "RFIDActi

Answer 1

In restframework, serializer.save() has different behavior based on creation and update. If you pass instance to serializer, it will update the object, otherwise, it will create a new one

@api_view(['POST', 'PUT'])
def rfid_data(request, pk):
    """
    Update or delete a rfid data.
    """

    rfid_activation = {
         ...
    }

    if request.method == 'POST':
        rfid_serializer = RFIDActivationSerializer(data=rfid_activation)
        if rfid_serializer.is_valid():
            rfid_serializer.save()
            return Response(rfid_serializer.data,status=status.HTTP_201_CREATED)
        return return Response(rfid_serializer.data, status=status.HTTP_400_BAD_REQUEST)

    # PUT is used for object update
    elif request.method == 'PUT':
        rfid = RFIDActivation.objects.get(pk=pk)
        # pass instance to your serializer
        # pass partial=True to allow partial updates
        rfid_serializer = RFIDActivationSerializer(instance=rfid, data=rfid_activation, partial=True)
        if rfid_serializer.is_valid():
            rfid_serializer.save()
            return Response(rfid_serializer.data)
        return Response(rfid_serializer.errors, status=status.HTTP_400_BAD_REQUEST)

UPDATE

default is calculated at import time, in your case, your default value for activation_id is calculated once and never change for subsequent instances. You have to define a function, thus default callable will be updated each time on object creation, read more here

def activation_id_generator(self):
    return uuid4().hex[:8]

# then in your class
class RFIDActivation(models.Model):
    ...
    ActivationId = models.CharField(max_length=10, unique=True, default=activation_id_generator)