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详解从Django Rest Framework响应中删除空字段

yipeiwu_com7年前 (2020-03-06)Python基础

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

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