[FIXED] serializer method to set the value of an attribute doesn't work in a post request. I am using Django Rest Framework

Issue

I have a model which has an attribute "transaction_id" which is a customized ID field and it's value has to be calculated in order to be saved in the database.

I have a model:

class Transaction(models.Model):
     field = models.IntegerField(default=0)
     transaction_id = models.UUIDField(unique=True)

This is the seriaizer:

class TransactionSerializer(serializers.ModelSerializer):
    class Meta:
        model = Transaction
        fields = '__all__'
        read_only_fields = ['id', 'transaction_id']

    def set_tn_number(self):
        tn_number = "some_string/"
        #I have to perform some calculation in order to get the relevant value
        tn_number = tn_number + str(10)
        return tn_number

Now in my post method of the view, i am performing the following:

def post(self, request):
        serializer = TransactionSerializer(data=request.data)
        if serializer.is_valid():
            serializer.tn_number = serializer.set_tn_number()
            serializer.save()
            message = {'message': "Transaction Created Successfully"}
            return Response(message, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

But i am still getting integrity error:

NOT NULL constraint failed: transaction_transaction.transaction_id

Can someone please help me with this?

Thank you for your time

Solution

Update validated data or pass the necessary model attributes to save method as kwargs.

def post(self, request):
    serializer = TransactionSerializer(data=request.data)
    if serializer.is_valid():
        tn_number = serializer.set_tn_number()
        serializer.save(transaction_id=tn_number)
        message = {'message': "Transaction Created Successfully"}
        return Response(message, status=status.HTTP_201_CREATED)
    return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

Answered By - Avinash Raj