Django-rest-framework: Nested serializer field required when required = False

[Anton-Shutik]

Hi there,

I'm on DRF 3.1.0 and Django 1.7.6 and have serializers like below:

class AddressSerializer(serializers.ModelSerializer):
    zip = serializers.RegexField(regex=r'^\d{5}(-\d{4})?$')
    addr1 = serializers.Field()

    class Meta:
        model = Address

class CustomerSerializer(serializers.ModelSerializer):
    ship_address = AddressSerializer(required=False)
    email = serializers.Field()

    class Meta:
        model = Customer

and it works fine when doing like this (usual dict):

CustomerSerializer(data={'email':'[email protected]'}).is_valid() # Gives True, which is ok

BUT it fails when serializer created with request.data in the view, because request.data has MergeDict type

from rest_framework.requests import MergeDict
cs=CustomerSerializer(data=MergeDict({'email':'[email protected]'})) 
cs.is_valid()# Gives False
cs.errors # {'ship_address': {'zip': [u'This field is required.'], 'addr1': [u'This field is required.']}}

I understand that 'zip' and 'addr1' required fields on Address, but in this case Address is not required at all.

Am I doing smth wrong or any ideas how to fix that ?

Thanks in advance

[tomchristie]

Please send usage questions to the discussion group, IRC or stack overflow.
The issue tracker is for managing bugs, feature requests and other active work on the project.

Thanks! :)

[Anton-Shutik]

@tomchristie This looks like a bug,
I also found a person with same problem here https://groups.google.com/forum/?fromgroups#!topic/django-rest-framework/ttq8PUAU424

[variable]

Having same problem in viewset

class CommentSerializer(serializers.ModelSerializer):
    created_by = UserSerializer(required=False)
    content = serializers.PrimaryKeyRelatedField(queryset=Content.objects.all(), required=False)

    class Meta:
        model = Comment

keeps saying the fields in created_by are required.

[variable]

Hi @tomchristie, just wondering if this will be fixed anytime soon?

[xordoquy]

@variable if you need to speed up the process the best way is to help us with a pull request.

[tomchristie]

Unclear to me if this is a duplicate of #2919.

[tomchristie]

Hi @variable

keeps saying the fields in created_by are required.

Could you expand on that? What's the error message, and what code is being run that causes it?

[tomchristie]

Probably not a duplicate. First step is to write the _most minimal possible_ failing test case.

[variable]

@tomchristie I am not able to reproduce in test case:

class CommentTestCase(TestCase):

    def test_comment(self):
        self.assertEqual(Comment.objects.count(), 0)
        user = User.objects.create_user('testuser', '[email protected]', 'password')
        post = Post.objects.create(created_by=user)
        factory = APIRequestFactory()
        req = factory.post('/api/comments/comments/?content_uuid={}'.format(post.uuid), data={
            'message': 'abc'
        }, format='json')
        force_authenticate(req, user=user)
        CommentViewSet.as_view({'post': 'create'})(req)
        self.assertEqual(Comment.objects.count(), 1)

    def test_comment_1(self):
        self.assertEqual(Comment.objects.count(), 0)
        user = User.objects.create_user('testuser', '[email protected]', 'password')
        post = Post.objects.create(created_by=user)
        client = APIClient()
        client.login(username='testuser', password='password')
        result = client.post('/api/comments/comments/?content_uuid={}'.format(post.uuid), data={
            'message': 'abc'
        }, format='json')
        self.assertEqual(Comment.objects.count(), 1)

The only difference is I am posting via Ajax post, does it make any difference?

    $.post('/api/comments/comments/?content_uuid='+uuid, {message: msg}, function(data){}, 'json');

[variable]

@tomchristie
I have added "read_only=True" to the created_by field now it works in ajax post, but it seems the read_only flag is trivial since "required=False"

[tomchristie]

Given this "I am not able to reproduce in test case:" I'm going to assume this was a duplicate of #2919 (just closed now), and close this. More than happy to reconsider if anyone can expand on this with a failing example case.

[sandeepginside]

I m having exactly the same problem. As mentioned by Anton,

class AddressSerializer(serializers.ModelSerializer):
    class Meta:
        model = Address
        fields = ['house_number', 'street', 'area', 'locality', 'address_of']

class CustomerSerializer(serializers.ModelSerializer):
    ship_address = AddressSerializer(required=False)

    class Meta:
        model = Customer

In Address model Street is a required field.

I want to have the ship_address to be optional in CustomerSerializer.
Inspite of having the required=False flag, I m getting a validation error :

"ship_address": {
        "street": [
            "This field may not be blank."
        ]
    }

Please suggest...

[xordoquy]

The discussion group is the best place to take this point and other usage questions. Thanks!

[mihailb]

Looks like this issue was never fixed. Having the same problem as @Anton-Shutik and @sandeepginside and it is not a duplicate of #2919
@xordoquy @tomchristie Can this issue be reopened?

[rpkilby]

Hi @mihailb. The easiest place to start would be to turn https://github.com/encode/django-rest-framework/issues/2719#issuecomment-393644095 into a failing test case/PR.

[francisjeanneau]

Why is this closed? Looks like an important bug to me and can't see any info on that elsewhere. Is there a work around?

By using a custom name instead of the model field name and specifying the source parameter to the serializer, the problem goes away. ie:

user_details = UserSerializer(
    read_only=True,
    source='user',
)

instead of

user = UserSerializer(
    read_only=True,
)

which generates a HTTP 400 field required. Note that this prevents the use of the depth attribute in the serializer's Meta class.

Also, @tomchristie refers this issue in a reply in the mailing list, however no informations help to overcome the problem here. (https://groups.google.com/forum/#!topic/django-rest-framework/ttq8PUAU424)

[rpkilby]

Reopening, since @sandeepginside's example should be enough to create a test case.

[beda42]

Just a hint for some of you experiencing this - I found that in my case it was caused by a unique_together constrain on the model which forced the field at hand to behave as required=True.
This case is documented in the docs here: https://www.django-rest-framework.org/api-guide/validators/#optional-fields

[therealak12]

May be this answer solves your problem:
allow_null