How can I return a dict object from within to_representation method of RelatedField in Django rest framework?

I have a custom field like this:

class TagField(serializers.RelatedField):
    def to_representation(self, value):
        resp = {
            'name': value.name,
            'categoryid': value.categoryid.pk
        }
        return resp 

I'm getting an error which says 'dict' object is not hashable. Why does this happen? How can I get it to work?