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

Also:

try:
   serializer.instance = YourModel.objects.get(...)
except YourModel.DoesNotExist:
   pass

if serializer.is_valid():
   serializer.save()    # will INSERT or UPDATE your validated data

Answer 2

I would use the serializers' create method.

In it you could check if the question (with the ID of it you provide in the 'question' primary key related field) already has an answer, and if it does, fetch the object and update it, otherwise create a new one.

So the first option would go something like:

class AnswerSerializer(serializers.ModelSerializer):
    question = serializers.PrimaryKeyRelatedField(many=False, queryset=Question.objects.all())

    class Meta:
        model = Answer
        fields = (
            'id',
            'answer',
            'question',
        )

    def create(self, validated_data):
        question_id = validated_data.get('question', None)
        if question_id is not None:
            question = Question.objects.filter(id=question_id).first()
            if question is not None:
                answer = question.answer
                if answer is not None:
                   # update your answer
                   return answer

        answer = Answer.objects.create(**validated_data)
        return answer

Second option would be to check if the answer with the answer id exists.

Answer ID's wouldn't show up in the validated data of post requests, unless you used a sort of workaround and manually defined them as read_only = false fields:

id = serializers.IntegerField(read_only=False)

But you should however rethink this through, There's a good reason the PUT method and the POST methods exist as separate entities, and you should separate the requests on the frontend.