Setting a default value for an instance in django views

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I am tracking histories on my models using simple history and this works fine. Problem is, some changes made to the models are done by the application and so do not have a history_user, thus return null. The result I get form the API in this case is as below. I am trying return the id of the history_user for those that have one and set the ones that are null to a specific id, say 1. But am struggling a bit. I have added a function get_history_user to return 1 in case the value is null. But the code just runs and returns the initial result with no errors. Can this work as it is? What am I doing wrong?

Edit I have managed to get the function to work and it returns a 1 as intended. But returning the invoice history still returns the null as below. I need some help tweaking this so that invoice_history picks the history_user from the function and appends it to the result.

{
    "history_id": 509,
    "history_user": null,
    "history_type": "+",
    "history_date": "2021-05-03T16:17:53.558643+03:00",
    "id": 976
}

Views.py

class AllHistoryView(APIView):
    def get(self, request, format=None):
        all_invhist = Invoice.history.all()
        serializers = InvoiceHistorySerializer(all_invhist, many=True)
        try:
            result = {}
            res = serializers.data
            # result = res
            invoice_history = res[0]

            def get_history_user(invoice_history):
                history_user = invoice_history["history_user"]

                if isinstance(history_user, (float, int)):
                    return history_user

                return 1  # use 1 instead of null
            rez = get_history_user(invoice_history) #rez prints 1
            return Response(invoice_history, status=status.HTTP_200_OK) 

        except Exception as e:
            error = getattr(e, "message", repr(e))
            print(error)
            result["errors"] = error
            result["status"] = "error"

        return Response(result, status=status.HTTP_400_BAD_REQUEST)
django python
1 Answers

From what I can tell here, it looks like you are trying to get the id of the first history_user if it exists. You can achieve this without serializing and deserializing the objects.

class AllHistoryView(APIView):
    def get(self, request, format=None):
        inv_first = Invoice.history.all().first()
        if inv_first is not None:
            return Response(inv_first.history_user.pk)  # the default status code is 200
        else:
            return Response(1, status=status.HTTP_400_BAD_REQUEST)
user_32620540
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