在Python類中序列化@property方法

Question

在序列化Django模型類時，有沒有辦法將任何@property定義傳遞給json序列化程序？

例如：

class FooBar(object.Model) 

    name = models.CharField(...) 

    @property 
    def foo(self): 
     return "My name is %s" %self.name 

要序列化到：

def list_class_properties(cls): 
    return [k for k,v in cls.__dict__.iteritems() if type(v) is property] 

例如：

[{ 

    'name' : 'Test User', 

    'foo' : 'My name is Test User', 
},] 

Answer 1

你可以使用一些魔法讓所有類的屬性：

>>> class Foo: 
     @property 
     def bar(self): 
      return "bar" 

>>> list_class_properties(Foo) 
['bar'] 

然後你可以建立字典並從那裏序列化它。

Answer 2

您可以擴展Django的序列化程序，而不需要做太多的工作。這是一個自定義序列化程序，它接受查詢集和屬性列表（不是字段），並返回JSON。

from StringIO import StringIO 
from django.core.serializers.json import Serializer 

class MySerializer(Serializer): 
    def serialize(self, queryset, list_of_attributes, **options): 
     self.options = options 
     self.stream = options.get("stream", StringIO()) 
     self.start_serialization() 
     for obj in queryset: 
      self.start_object(obj) 
      for field in list_of_attributes: 
       self.handle_field(obj, field) 
      self.end_object(obj) 
     self.end_serialization() 
     return self.getvalue() 

    def handle_field(self, obj, field): 
     self._current[field] = getattr(obj, field) 

用法：

>>> MySerializer().serialize(MyModel.objects.all(), ["field1", "property2", ...]) 

當然，這不只是寫自己的簡單的JSON序列可能更多的工作，但也許比你自己的XML序列化沒有更多的工作（你必須重新定義「handle_field」除了更改基類以外，還匹配XML案例）。

Answer 3

事情自2010年以來有所改變，所以@ user85461的答案似乎不再適用於Django 1.8和Python 3.4。這是一個更新的答案，似乎對我有用。

from django.core.serializers.base import Serializer as BaseSerializer 
from django.core.serializers.python import Serializer as PythonSerializer 
from django.core.serializers.json import Serializer as JsonSerializer 
from django.utils import six 

class ExtBaseSerializer(BaseSerializer): 
    """ Abstract serializer class; everything is the same as Django's base except from the marked lines """ 
    def serialize(self, queryset, **options): 
     self.options = options 

     self.stream = options.pop('stream', six.StringIO()) 
     self.selected_fields = options.pop('fields', None) 
     self.selected_props = options.pop('props', None) # added this 
     self.use_natural_keys = options.pop('use_natural_keys', False) 
     self.use_natural_foreign_keys = options.pop('use_natural_foreign_keys', False) 
     self.use_natural_primary_keys = options.pop('use_natural_primary_keys', False) 

     self.start_serialization() 
     self.first = True 
     for obj in queryset: 
      self.start_object(obj) 
      concrete_model = obj._meta.concrete_model 
      for field in concrete_model._meta.local_fields: 
       if field.serialize: 
        if field.rel is None: 
         if self.selected_fields is None or field.attname in self.selected_fields: 
          self.handle_field(obj, field) 
        else: 
         if self.selected_fields is None or field.attname[:-3] in self.selected_fields: 
          self.handle_fk_field(obj, field) 
      for field in concrete_model._meta.many_to_many: 
       if field.serialize: 
        if self.selected_fields is None or field.attname in self.selected_fields: 
         self.handle_m2m_field(obj, field) 
      # added this loop 
      if self.selected_props: 
       for field in self.selected_props: 
        self.handle_prop(obj, field) 
      self.end_object(obj) 
      if self.first: 
       self.first = False 
     self.end_serialization() 
     return self.getvalue() 

    # added this function 
    def handle_prop(self, obj, field): 
     self._current[field] = getattr(obj, field) 


class ExtPythonSerializer(ExtBaseSerializer, PythonSerializer): 
    pass 


class ExtJsonSerializer(ExtPythonSerializer, JsonSerializer): 
    pass 

用法：

>>> ExtJsonSerializer().serialize(MyModel.objects.all(), fields=['myfield', ...], props=['myprop', ...]) 

Answer 4

該解決方案行之有效由M. Rafay阿利姆和Wtower提出，但它的重複大量的代碼。下面是一個改良效果：

from django.core.serializers.base import Serializer as BaseSerializer 
from django.core.serializers.python import Serializer as PythonSerializer 
from django.core.serializers.json import Serializer as JsonSerializer 

class ExtBaseSerializer(BaseSerializer): 

    def serialize_property(self, obj): 
     model = type(obj) 
     for field in self.selected_fields: 
      if hasattr(model, field) and type(getattr(model, field)) == property: 
       self.handle_prop(obj, field) 

    def handle_prop(self, obj, field): 
     self._current[field] = getattr(obj, field) 

    def end_object(self, obj): 
     self.serialize_property(obj) 

     super(ExtBaseSerializer, self).end_object(obj) 


class ExtPythonSerializer(ExtBaseSerializer, PythonSerializer): 
    pass 


class ExtJsonSerializer(ExtPythonSerializer, JsonSerializer): 
    pass 

如何使用它：

ExtJsonSerializer().serialize(MyModel.objects.all(), fields=['field_name_1', 'property_1' ...]) 

Answer 5

這是M. Rafay阿利姆和Wtowers答案，caots的組合。 這是DRY，並且只允許您指定額外的道具，而不是像caots版本中的所有字段和道具。

from django.core.serializers.json import Serializer as JsonSerializer 
from django.core.serializers.python import Serializer as PythonSerializer 
from django.core.serializers.base import Serializer as BaseSerializer 

class ExtBaseSerializer(BaseSerializer): 
    def serialize(self, queryset, **options): 
     self.selected_props = options.pop('props') 
     return super(ExtBaseSerializer, self).serialize(queryset, **options) 

    def serialize_property(self, obj): 
     model = type(obj) 
     for field in self.selected_props: 
      if hasattr(model, field) and type(getattr(model, field)) == property: 
       self.handle_prop(obj, field) 

    def handle_prop(self, obj, field): 
     self._current[field] = getattr(obj, field) 

    def end_object(self, obj): 
     self.serialize_property(obj) 

     super(ExtBaseSerializer, self).end_object(obj) 

class ExtPythonSerializer(ExtBaseSerializer, PythonSerializer): 
    pass 

class ExtJsonSerializer(ExtPythonSerializer, JsonSerializer): 
    pass 

如何使用它：

ExtJsonSerializer().serialize(MyModel.objects.all(), props=['property_1', ...])