PUT method not updating nested serializer due to 'unique' field restriction

[mbaragiola]

Checklist

• [] I have verified that that issue exists against the master branch of Django REST framework.

Did a clean pyvenv-3.5 workspace and git cloned master.

• [] I have searched for similar issues in both open and closed tickets and cannot find a duplicate.

Couldn't find anything, but perhaps I'm describing wrong my issue.

• This is not a usage question. (Those should be directed to the discussion group instead.)
• This cannot be dealt with as a third party library. (We prefer new functionality to be in the form of third party libraries where possible.)
• I have reduced the issue to the simplest possible case.

Created a clean test project.

• I have included a failing test as a pull request. (If you are unable to do so we can still accept the issue.)

Not yet!

Steps to reproduce

models.py

from django.db import models


class Person(models.Model):
    name = models.CharField(
        max_length=100,
        unique=True
    )


class PersonExtension(models.Model):
    person = models.OneToOneField(
        Person
    )
    extra_data = models.CharField(
        max_length=100,
        default="",
        blank=True
    )

serializers.py

from rest_framework.serializers import HyperlinkedModelSerializer

from prueba import models


class PersonSerializer(HyperlinkedModelSerializer):

    class Meta:
        model = models.Person
        fields = (
            'url',
            'id',
            'name'
        )

class PersonExtensionSerializer(HyperlinkedModelSerializer):
    person = PersonSerializer()

    class Meta:
        model = models.PersonExtension
        fields = (
            'url',
            'id',
            'person',
            'extra_data'
        )

    def create(self, validated_data):
        person_data = validated_data.pop('person')
        person, created = models.Person.objects.update_or_create(
            pk=person_data.get('id'),
            defaults=person_data
        )
        validated_data['person'] = person
        person_extension = models.PersonExtension.objects.create(
            **validated_data
        )
        return person_extension

    def update(self, instance, validated_data):
        person_data = validated_data.get('person')
        instance.person.name = person_data.get(
            'name',
            instance.person.name
        )
        instance.person.save()
        instance.extra_data = validated_data.get(
            'extra_data',
            instance.extra_data
        )
        instance.save()
        return instance

views.py

from rest_framework.viewsets import ModelViewSet

from prueba import models, serializers


class PersonViewSet(ModelViewSet):
    queryset = models.Person.objects.all()
    serializer_class = serializers.PersonSerializer


class PersonExtensionViewSet(ModelViewSet):
    queryset = models.PersonExtension.objects.all()
    serializer_class = serializers.PersonExtensionSerializer

urls.py

from django.conf.urls import url, include
from rest_framework.routers import DefaultRouter

from prueba import views

router = DefaultRouter()
router.register(r'persons', views.PersonViewSet)
router.register(r'personextensions', views.PersonExtensionViewSet)

urlpatterns = [
    url(r'^', include(router.urls)),
]

Expected behavior

POST to localhost:8000/personextensions/

{
    "person": {
        "name": "Hello"
    },
    "extra_data": ""
}

Person and PersonExtension are both created successfully.

PUT to localhost:8000/personextensions/1/

{
    "url": "http://localhost:8000/personextensions/1/",
    "id": 1,
    "person": {
        "url": "http://localhost:8000/persons/1/",
        "id": 1,
        "name": "Hello"
    },
    "extra_data": "How are you?"
}

extra_data successfully modified to "How are you?"

PUT to localhost:8000/personextensions/1/

{
    "url": "http://localhost:8000/personextensions/1/",
    "id": 1,
    "person": {
        "url": "http://localhost:8000/persons/1/",
        "id": 1,
        "name": "Hello 1"
    },
    "extra_data": "How are you?"
}

Successfully changed name to "Hello 1" and extra_data to "How are you?".

Actual behavior

POST to localhost:8000/personextensions/

{
    "person": {
        "name": "Hello"
    },
    "extra_data": ""
}

Person and PersonExtension are both created successfully.

PUT to localhost:8000/personextensions/1/

{
    "url": "http://localhost:8000/personextensions/1/",
    "id": 1,
    "person": {
        "url": "http://localhost:8000/persons/1/",
        "id": 1,
        "name": "Hello"
    },
    "extra_data": "How are you?"
}

Error: "Person with this name already exists."

PUT to localhost:8000/personextensions/1/

{
    "url": "http://localhost:8000/personextensions/1/",
    "id": 1,
    "person": {
        "url": "http://localhost:8000/persons/1/",
        "id": 1,
        "name": "Hello 1"
    },
    "extra_data": "How are you?"
}

Successfully changed name to "Hello 1" and extra_data to "How are you?".

Thanks in advance!

[tomchristie]

Duplicate of #2996.

We can't automagically handle unique constraints on nested serializers. Specify the name field on the serializer explicitly (so that it doesn't magically include the validator). You'll then need to enforce the uniqueness explicitly instead (eg in the .validate() method of the parent serializer)

[isasiluis28]

Did this solve the problem ?

[pagereborn]

I am facing the same issue, I updated to the latest version and the issue persists.
I think the issue still exists. It's a different issue than #2996

[xordoquy]

Either specify the name explicitely on the serializer or use the extra_kwargs to get rid of the unique validator. Either way work and it's not different from #2996 or you have a different issue