详解从Django Rest Framework响应中删除空字段


						我使用django-rest-framework开发了一个API.

我正在使用ModelSerializer返回模型的数据.

models.py





class MetaTags(models.Model):

 title = models.CharField(_('Title'), max_length=255, blank=True, null=True)

 name = models.CharField(_('Name'), max_length=255, blank=True, null=True)





serializer.py





class MetaTagsSerializer(serializers.ModelSerializer):

 class Meta:

  model = MetaTags





响应





{

 "meta": {

  "title": null,

  "name": "XYZ"

 }

}





理想情况下,在API响应中,不应在响应中发送任何不存在的值.

当标题为null时,我希望响应为：





{

 "meta": {

  "name": "XYZ"

 }

}





您可以尝试覆盖to_native函数：





class MetaTagsSerializer(serializers.ModelSerializer):

 class Meta:

  model = MetaTags



 def to_native(self, obj):

  """

  Serialize objects -> primitives.

  """

  ret = self._dict_class()

  ret.fields = self._dict_class()



  for field_name, field in self.fields.items():

   if field.read_only and obj is None:

    continue

   field.initialize(parent=self, field_name=field_name)

   key = self.get_field_key(field_name)

   value = field.field_to_native(obj, field_name)



   # Continue if value is None so that it does not get serialized.

   if value is None:

    continue



   method = getattr(self, 'transform_%s' % field_name, None)

   if callable(method):

    value = method(obj, value)

   if not getattr(field, 'write_only', False):

    ret[key] = value

   ret.fields[key] = self.augment_field(field, field_name, key, value)



  return ret







我基本上从serializers.BaseSerializer复制了基本的to_native函数,并添加了一个值的检查.

更新：

至于DRF 3.0,to_native()被重命名为to_representation(),其实现稍有改变.这是DRF 3.0的代码,它忽略空值和空字符串值：





def to_representation(self, instance):

 """

 Object instance -> Dict of primitive datatypes.

 """

 ret = OrderedDict()

 fields = self._readable_fields



 for field in fields:

  try:

   attribute = field.get_attribute(instance)

  except SkipField:

   continue



  # KEY IS HERE:

  if attribute in [None, '']:

   continue



  # We skip `to_representation` for `None` values so that fields do

  # not have to explicitly deal with that case.

  #

  # For related fields with `use_pk_only_optimization` we need to

  # resolve the pk value.

  check_for_none = attribute.pk if isinstance(attribute, PKOnlyObject) else attribute

  if check_for_none is None:

   ret[field.field_name] = None

  else:

   ret[field.field_name] = field.to_representation(attribute)



 return ret







翻译自：http://stackoverflow.com/questions/27015931/remove-null-fields-from-django-rest-framework-response



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