drf2.py

class SerializerMethodKwargField(serializers.SerializerMethodField):
    def __init__(self, *args, **kwargs):
        default_args = [
            'read_only', 'write_only', 'required', 'default', 'initial', 'source', 'label',
            'help_text', 'style', 'error_messages', 'validators', 'allow_null']

        kwargs_to_del = []
        self.method_kwargs = {}
        for kwarg in kwargs:
            if kwarg not in default_args:
                if kwarg == 'method':
                    self.method = kwargs[kwarg]
                else:
                    self.method_kwargs.update({
                        kwarg: kwargs[kwarg],
                    })
                kwargs_to_del.append(kwarg)

        for kwarg in kwargs_to_del:
            del kwargs[kwarg]

        super(SerializerMethodKwargField, self).__init__(*args, **kwargs)

    def to_representation(self, obj):
        return getattr(obj, self.method)(**self.method_kwargs)
    
class MyModelSerializer(serializers.ModelSerializer):
    avatar = SerializerMethodKwargField(source='*', method='get_avatar')
    avatar_sm = SerializerMethodKwargField(source='*', method='get_avatar', size='small')
    
    class Meta:
        model = MyModel
        fields = ('avatar', 'avatar_sm',)
    
class MyModel(models.Model):
    avatar = models.ImageField(...)
    
    def get_avatar(self, size='default'):
        if size == 'small':
            return 'small image'
        
        return 'original image'

options.py

class BooleanKwargField(serializers.BooleanField):
    def __init__(self, *args, **kwargs):
        default_args = [
            'read_only', 'write_only', 'required', 'default', 'initial', 'source', 'label',
            'help_text', 'style', 'error_messages', 'validators', 'allow_null']

        kwargs_to_del = []
        self.method_kwargs = {}
        for kwarg in kwargs:
            if kwarg not in default_args:
                if kwarg == 'method':
                    self.method = kwargs[kwarg]
                else:
                    self.method_kwargs.update({
                        kwarg: kwargs[kwarg],
                    })
                kwargs_to_del.append(kwarg)

        for kwarg in kwargs_to_del:
            del kwargs[kwarg]

        super(SerializerMethodKwargField, self).__init__(*args, **kwargs)

    def to_representation(self, obj):
        return getattr(obj, self.method)(**self.method_kwargs)