required=False not working with update_or_create in ModelSerializer - django

Question

I am creating an API where I get some data with user_id field. If given user_id exist in DB it update rest of the data else it will create new data. Here my code:
serializers.py
class DataUpdateSerializer(serializers.ModelSerializer):
user_id = serializers.CharField(max_length=250)
email = serializers.EmailField(required=False)
first_name = serializers.CharField(required=False)
last_name = serializers.CharField(required=False)
class Meta:
model = User
fields = ('first_name', 'last_name', 'email', 'user_id', 'balance', 'device_id', 'platform')
def create(self, validated_data):
data_update, created = User.objects.update_or_create(user_id=validated_data['user_id'],
defaults={
'first_name': validated_data['first_name'],
'last_name': validated_data['last_name'],
'email': validated_data['email'],
'balance': validated_data['balance'],
'device_id': validated_data['device_id'],
'platform': validated_data['platform'],
}
)
return data_update
views.py
class data_update(APIView):
permission_classes = (Check_API_KEY_Auth,)
def post(self, request):
serializer = DataUpdateSerializer(data=request.data)
if serializer.is_valid():
serializer.save()
username = request.data['user_id']
User.objects.filter(user_id=username).update(username=username)
return Response(serializer.data, status=status.HTTP_201_CREATED)
else:
return Response(serializer.errors, status=status.HTTP_204_NO_CONTENT)
email, first_name and last_name are optional and can be blank in DB or in serializer.
Models.py
class User(AbstractUser):
device_id = models.CharField(max_length=250)
balance = models.FloatField()
platform = models.CharField(max_length=250)
user_id = models.CharField(max_length=250, unique=True)
Problem:
Everything is working fine but if I don't pass email, first_name or last_name, it gives error: key_error and if I provide these fields with blank value "", this give error cannot be blank

Answer 1

I see various problems in your code.
In the declaration of CharField in the model, you don't have blank=True. Hence, they simply cannot be blank in the DB, whatever you do above.
Be careful when using a very basic APIView and manipulating the seralizer yourself. Your view is called "Update" but it does both "create" and "update". These are two different things, usually handled by two different routes.
The usage you make of your serializer DataUpdateSerializer(data=request.data) is the usage for a CREATE, not an UPDATE, where you pass the instance of the relevant model object as first argument.
The usage you make of objects.update_or_create must be checked. You basically make a queryset filtering using fields that may or may not be present, whose values may or may not have been changed, and if by any chance that filtering makes any sense, and you get nothing in return, then you create the object...
I would suggest to split the routes. Make a ListAPIView where you can CREATE, and a RetrieveUpdateDestroyAPIView taking the user_id as parameter in your REST route, and simply declare the serializer class in the views. Then, use the create and update methods of the serializer itself. However, if everything is simply declared, you'd rarely need to write anything in these methods.