      choices = property(_get_choices, _set_choices)
  
      ### Regular serializer stuff...
  
      def field_to_native(self, obj, field_name):
          try:
 
</s> remove             value = [] if self.many else None
 </s> add             value = self.get_default_value() </s> remove                 if is_simple_callable(self.default):
                    native = self.default()
                else:
                    native = self.default
 </s> add                 native = self.get_default_value()
    ### Default value handling

    def get_default_value(self):
        default = super(RelatedField, self).get_default_value()
        return default or \
            [] if self.many else None

      choices = property(_get_choices, _set_choices)
  
    ### Default value handling

    def get_default_value(self):
        default = super(RelatedField, self).get_default_value()
        return default or \
            [] if self.many else None

      ### Regular serializer stuff...
  
      def field_to_native(self, obj, field_name):
          try:
keep add keep keep keep keep
 RelatedField default value handling fixed 
rest_framework/relations.py