This looks like a *bug in Django REST Framework (DRF) 3.16.0*, where the
UniqueConstraint might be affecting field serialization. In *DRF 3.15.2*,
the foo field was included, but in *DRF 3.16.0*, it disappears.
*Possible Workarounds* 1. *Explicitly Declare foo in Meta.fields*
Since foo is being removed when using UniqueConstraint, you can *explicitly
list it* in Meta.fields:
class BaseModelSerializer(ModelSerializer):
foo = SerializerMethodField()
class Meta:
model = None # Override in subclasses
fields = ("id", "foo", "bar") # Explicitly include `foo`
@staticmethod
def get_foo(obj) -> int | None:
return obj.foo
2. *Use extra_kwargs to Force Inclusion*
Another workaround is using extra_kwargs in the serializer:
class BaseModelSerializer(ModelSerializer):
class Meta:
model = None # Override in subclasses
fields = ("id", "foo", "bar")
extra_kwargs = {"foo": {"read_only": True}}
3. *Manually Add foo in to_representation*
If the issue persists, override to_representation to *ensure foo is
serialized*:
class BaseModelSerializer(ModelSerializer):
class Meta:
fields = ("id", "bar") # Exclude `foo` here to manually add
def to_representation(self, instance):
data = super().to_representation(instance)
data["foo"] = instance.foo # Ensure `foo` is added back
return data
On Tue, 1 Apr 2025 at 09:52, Martin Reidemeister <
[email protected]> wrote:
> I experience a bug with DRF 3.16.0.
>
> I created a minimal example:
>
> # model.py
> from django.db.models import CharField, IntegerField, Model,
> UniqueConstraint
>
> class MyModel(Model):
> class Meta:
> abstract = True
>
> foo = IntegerField(null=True, blank=True)
> bar = CharField(max_length=100)
>
>
> class ModelWithoutUniqueConstraint(MyModel):
> pass
>
> class ModelWithUniqueConstraint(MyModel):
> class Meta:
> constraints = [UniqueConstraint(fields=("bar", "foo"),
> name="unique_bar_and_foo", nulls_distinct=False)]
>
> # view_rest.py
> from rest_framework.fields import SerializerMethodField
> from rest_framework.serializers import ModelSerializer
> from rest_framework.viewsets import ReadOnlyModelViewSet
>
> from myapp.models import ModelWithoutUniqueConstraint,
> ModelWithUniqueConstraint
>
>
> class BaseModelSerializer(ModelSerializer):
> class Meta:
> fields = ("id", "foo", "bar")
>
> foo = SerializerMethodField()
>
> @staticmethod
> def get_foo(obj: ModelWithUniqueConstraint) -> int | None:
> return obj.foo
>
> class ModelWithUniqueConstraintSerializer(BaseModelSerializer):
> class Meta(BaseModelSerializer.Meta):
> model = ModelWithUniqueConstraint
>
> class ModelWithoutUniqueConstraintSerializer(BaseModelSerializer):
> class Meta(BaseModelSerializer.Meta):
> model = ModelWithoutUniqueConstraint
>
> class ModelWithUniqueConstraintViewSet(ReadOnlyModelViewSet):
> queryset = ModelWithUniqueConstraint.objects.all()
> serializer_class = ModelWithUniqueConstraintSerializer
>
> class ModelWithoutUniqueConstraintViewSet(ReadOnlyModelViewSet):
> queryset = ModelWithoutUniqueConstraint.objects.all()
> serializer_class = ModelWithoutUniqueConstraintSerializer
>
> In the result of ModelWithUniqueConstraintViewSet the field "foo" is lost
> whith DRF 3.16. while it works with 3.15.2
>
> My current dependencies are:
> asgiref==3.8.1
> attrs==25.3.0
> django==5.1.7
> djangorestframework==3.16.0
> drf-spectacular==0.28.0
> inflection==0.5.1
> jsonschema==4.23.0
> jsonschema-specifications==2024.10.1
> pyyaml==6.0.2
> referencing==0.36.2
> rpds-py==0.24.0
> sqlparse==0.5.3
> typing-extensions==4.13.0 ; python_full_version < '3.13'
> tzdata==2025.2 ; sys_platform == 'win32'
> uritemplate==4.1.1
>
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>
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