DRF serializer depth makes fields ignored on create

Question

(project is available on github with that problem)

For some reason serializer's depth option makes fields ignored on create.

Serializer:

class AnswerSerializer(serializers.ModelSerializer):

    class Meta:
        model = Answer
        fields = ('question', 'body',)
        depth = 1

View:

class AnswerList(ListCreateAPIView):
    queryset = Answer.objects.all()
    serializer_class = AnswerSerializer

When I try to create an answer with depth = 1 I get NOT NULL constraint failed: forum_answer.question_id, but when I comment out depth = 1 everything works. But of course I don't get a full Question object, only pk of it.

score 6 · Accepted Answer · answered Mar 02 '18 at 11:50

6

Found a better solution here

Now serializer looks like that:

class AnswerSerializer(serializers.ModelSerializer):
    question_pk = serializers.PrimaryKeyRelatedField(
        queryset=Question.objects.all(), source='question', write_only=True
    )

    class Meta:
        model = Answer
        fields = ('question', 'question_pk', 'body',)
        depth = 1

ps. Also commited to the project on github.

answered Mar 02 '18 at 11:50

Simon Moshenko

2,028
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What would you do for a ManyToManyField that's also failing because of the same problem with depth – Jorge Alberto Díaz Orozco Sep 11 '19 at 20:35

score 3 · Answer 2 · answered Jan 28 '19 at 11:10

3

class DemoSerializer(serializers.ModelSerializer):
def __init__(self, instance=None, data=empty, **kwargs):
    if instance:
        setattr(self.Meta, 'depth', 1)
    else:
        setattr(self.Meta, 'depth', 0)
    super(DemoSerializer, self).__init__(instance, data, **kwargs)

class Meta:
    model = Demo
    fields = '__all__'
    depth = 0

answered Jan 28 '19 at 11:10

闵禹强

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2

2

Could you explain a bit why this code solves the issue? – Stoogy Jan 28 '19 at 11:18
I had the same problem, and this solution worked! what I'm guessing is that it tests if an object already exists in the db it sets its depth to 1, which means it's a GET request, if it's a POST request, it sets the value to 0 which makes it accept id values in a normal way as it always should be. – selmanioui Nov 21 '22 at 10:54

score 1 · Answer 3 · answered Mar 02 '18 at 11:40

1

IMPORTANT: I believe this method is very UNSECURE because anyone can edit nested objects.

You can use drf-writable-nested for such functionality. Updated the project on github if someone needs.

ps. be sure to use 'pk' field for nested objects if you don't want these objects to be created.

answered Mar 02 '18 at 11:40

Simon Moshenko

2,028
1
15
36

Hey, sorry to revive such an old thread, but what do you mean by your comment: ```ps. be sure to use 'pk' field for nested objects if you don't want these objects to be created.``` – krisbkreeme Aug 09 '22 at 18:05

DRF serializer depth makes fields ignored on create

3 Answers3

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