django-rest-framework serializer different fields

Question

I am new at Django and couldn't find solution for my problem.

The problem is to force specific serializer for include different amount of fields in case of utilizing different views. I would like to use 'id' field in my 1st view, and in 2nd view - 'id' and 'name' fields.

Here is my model.py

class Processing(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.CharField()
    description = models.CharField()

And here is my serializer.py

class ProcessingSerializer(serializers.ModelSerializer):
    id = serializers.ModelField(model_field=Processing()._meta.get_field('id'))
    class Meta:
        model = Processing
        fields = ('id', 'name')

Any help will be welcome.

Answer 1

You can also use the next approach:

class SelectSerializerMixin(object):
    serializer_class = None
    list_serializer_class = None
    retrieve_serializer_class = None
    update_serializer_class = None
    partial_update_serializer_class = None
    create_serializer_class = None

    def get_serializer_class(self):
        """
        Return the class to use for the serializer.
        Defaults to using `self.serializer_class`.
        """
        assert self.serializer_class is not None, (
            "'%s' should either include a `serializer_class` attribute, "
            "or override the `get_serializer_class()` method."
            % self.__class__.__name__
        )
        return getattr(self, f"{self.action}_serializer_class") or self.serializer_class

Then add this mixin to your ViewSet:

class MyModelViewSet(SelectSerializerMixin, ModelViewSet):
    queryset = models.MyModel.objects.all()
    serializer_class = serializers.SomeSerializer
    retrieve_serializer_class = serializers.AnotherSerializer
    list_serializer_class = serializers.OneMoreSerializer

But if you need a Serializer with a dynamic set of fields (ex. you have a handler but you need to return only specific fields in the response), you can use the approach from Ykh's answer.

https://stackoverflow.com/a/44064046/2818865

Answer 2

When someone just starts using DRF, a common mistake is to try to make the same Serializer do everything under the sun. Certainly I went down that path myself.

but life becomes a lot simpler when you use mutiple serializers for different tasks. You can easily switch serializers using the get_serializer_class method. Here is an example right from the manual that shows how to use one for admins and another for ordinary users

def get_serializer_class(self):
    if self.request.user.is_staff:
        return FullAccountSerializer
    return BasicAccountSerializer

Sometimes you want to use a single serializer for lists and another one for when providing details. Try something like this:

def get_serializer_class(self):
    if self.action == 'retrieve':
        return serializers.PlayerDetailSerializer
    else : 
        return serializers.PlayerSerializer

Life is much simpler this way.

Answer 3

class DynamicFieldsModelSerializer(ModelSerializer):
    """
    A ModelSerializer that takes an additional `fields` and 'exclude' argument that
    controls which fields should be displayed.
    """

    def __init__(self, *args, **kwargs):
        # Don't pass the 'fields' arg up to the superclass
        fields = kwargs.pop('fields', None)
        exclude = kwargs.pop('exclude', None)

        # Instantiate the superclass normally
        super(DynamicFieldsModelSerializer, self).__init__(*args, **kwargs)

        if fields is not None:
            # Drop any fields that are not specified in the `fields` argument.
            allowed = set(fields)
            existing = set(self.fields.keys())
            for field_name in existing - allowed:
                self.fields.pop(field_name)

        if exclude is not None:
            not_allowed = set(exclude)
            for exclude_name in not_allowed:
                self.fields.pop(exclude_name)



class UserCreateSerializer(DynamicFieldsModelSerializer):
    class Meta:
        model = User
        fields = ('username', 'tel', 'email', 'password')

use:

serializer = UserCreateSerializer(data=request.data, fields=('username', 'password', 'tel'))

or

serializer = UserCreateSerializer(data=request.data, fields=('username', 'password', 'email'))