Django Rest Framework POST Update if existing or create

Question

I am new to DRF. I read the API docs, maybe it is obvious but I couldn\'t find a handy way to do it.

I have an Answer object which has one-to-one relationship with a

Answer 1

I tried the serializer solution but it seems exception raised before hitting the serializer function create(self, validated_data). That's because I'm using ModelViewSet (which in turn using class CreatedModelMixin). Further study reveals that exception raised here:

rest_framework/mixins.py

class CreateModelMixin(object):
    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True) <== Here

Since I want to keep all features provided by framework, so I prefer capturing the exceptions and route over to update:

from rest_framework.exceptions import ValidationError

class MyViewSet(viewsets.ModelViewSet)

    def create(self, request, *args, **kwargs):
        pk_field = 'uuid'
        try:
            response = super().create(request, args, kwargs)
        except ValidationError as e:
            codes = e.get_codes()
            # Check if error due to item exists
            if pk_field in codes and codes[pk_field][0] == 'unique':
                # Feed the lookup field otherwise update() will failed
                lookup_url_kwarg = self.lookup_url_kwarg or self.lookup_field
                self.kwargs[lookup_url_kwarg] = request.data[pk_field]
                return super().update(request, *args, **kwargs)
            else:
                raise e
        return response

My app can always call POST /api/my_model/ with parameters (here, uuid = primary key).

However, would it be better if we handle this in update function?

    def update(self, request, *args, **kwargs):
        try:
            response = super().update(request, *args, **kwargs)
        except Http404:
            mutable = request.data._mutable
            request.data._mutable = True
            request.data["uuid"] = kwargs["pk"]
            request.data._mutable = mutable
            return super().create(request, *args, **kwargs)
        return response