old_contents: from radar.models.users import User
  from radar.serializers.fields import StringField, IntegerField
  from radar.serializers.models import ModelSerializer
  
  
  class TinyUserSerializer(ModelSerializer):
      id = IntegerField()
      username = StringField()
      email = StringField()
      first_name = StringField()
      last_name = StringField()
  
      class Meta:
          model_class = User
          fields = (
              'id',
              'username',
              'email',
              'first_name',
              'last_name'
          )
  
  
  class CreatedUserMixin(object):
      created_user = TinyUserSerializer(read_only=True)
  
      def get_model_exclude(self):
          model_exclude = super(CreatedUserMixin, self).get_model_exclude()
          model_exclude.add('created_user_id')
          return model_exclude
  
  
  class ModifiedUserMixin(object):
      modified_user = TinyUserSerializer(read_only=True)
  
      def get_model_exclude(self):
          model_exclude = super(ModifiedUserMixin, self).get_model_exclude()
          model_exclude.add('modified_user_id')
          return model_exclude
  
  
  class MetaSerializerMixin(CreatedUserMixin, ModifiedUserMixin):
      pass
  
new_contents: from radar.models.users import User
  from radar.serializers.fields import StringField, IntegerField, DateTimeField
  from radar.serializers.models import ModelSerializer
  
  
  class TinyUserSerializer(ModelSerializer):
      id = IntegerField()
      username = StringField()
      email = StringField()
      first_name = StringField()
      last_name = StringField()
  
      class Meta:
          model_class = User
          fields = (
              'id',
              'username',
              'email',
              'first_name',
              'last_name'
          )
  
  
  class CreatedUserMixin(object):
      created_user = TinyUserSerializer(read_only=True)
  
      def get_model_exclude(self):
          model_exclude = super(CreatedUserMixin, self).get_model_exclude()
          model_exclude.add('created_user_id')
          return model_exclude
  
  
  class ModifiedUserMixin(object):
      modified_user = TinyUserSerializer(read_only=True)
  
      def get_model_exclude(self):
          model_exclude = super(ModifiedUserMixin, self).get_model_exclude()
          model_exclude.add('modified_user_id')
          return model_exclude
  
  
  class CreatedDateMixin(object):
      created_date = DateTimeField(read_only=False)
  
  
  class ModifiedDateMixin(object):
      modified_date = DateTimeField(read_only=False)
  
  
  class MetaSerializerMixin(CreatedUserMixin, ModifiedUserMixin, CreatedDateMixin, ModifiedDateMixin):
      pass
  
subject: Add created and modified date mixins