Allow fields to be None

[greg-finley]

fields could be None if exclude is provided. Though I guess no way to represent in types that you need one or the other populated.

[sobolevn]

@greg-finley would you mind attaching a link to the DRF docs to this PR, please?

[greg-finley]

https://www.django-rest-framework.org/api-guide/serializers/#specifying-which-fields-to-include

[sobolevn]

Reopened to trigger the CI once again.

[intgr]

My understanding is that fields may be omitted. But that doesn't mean it can be set to None.

Per DRF documentation

class AccountSerializer(serializers.ModelSerializer):
    class Meta:
        model = Account
        exclude = ['users']

There's no fields = None here.

[greg-finley]

I have code similar to the below. It passes unit tests that the latter will exclude a field and return the other fields.

class AccountSerializer(serializers.ModelSerializer):
    class Meta:
        model = Account
        fields: Optional[Union[Sequence[str], Literal["__all__"]]] = '__all__'

class AccountHideUsersSerializer(AccountSerializer):
    class Meta(AccountSerializer.Meta):
        model = Account
        fields = None
        exclude = ['users']