使用 simplejson 序列化简单类对象的最简单方法

I've used this strategy in the past and been pretty happy with it: Encode your custom objects as JSON object literals (like Python dicts) with the following structure:

{ '__ClassName__': { ... } }

这实质上是一个单项dict，其单个键是指定编码对象类型的特殊字符串，其值是实例属性的dict.如果这有道理的话.

编码器和解码器的一个非常简单的实现(简化self 实际使用的代码)如下所示:

TYPES = { 'ParentClass': ParentClass,
          'ChildClass': ChildClass }


class CustomTypeEncoder(json.JSONEncoder):
    """A custom JSONEncoder class that knows how to encode core custom
    objects.

    Custom objects are encoded as JSON object literals (ie, dicts) with
    one key, '__TypeName__' where 'TypeName' is the actual name of the
    type to which the object belongs.  That single key maps to another
    object literal which is just the __dict__ of the object encoded."""

    def default(self, obj):
        if isinstance(obj, TYPES.values()):
            key = '__%s__' % obj.__class__.__name__
            return { key: obj.__dict__ }
        return json.JSONEncoder.default(self, obj)


def CustomTypeDecoder(dct):
    if len(dct) == 1:
        type_name, value = dct.items()[0]
        type_name = type_name.strip('_')
        if type_name in TYPES:
            return TYPES[type_name].from_dict(value)
    return dct

在这个实现中，假设您正在编码的对象将有一个from_dict()类的方法，该方法知道如何从从JSON解码的dict中重新创建实例.

It's easy to expand the encoder and decoder to support custom types (e.g. datetime objects).

EDIT，回答您的编辑:这样一个实现的好处是，它将自动编码和解码在TYPES映射中找到的任何对象的实例.这意味着它将自动处理这样的子类:

class ChildClass(object):
    def __init__(self):
        self.foo = 'foo'
        self.bar = 1.1
        self.parent = ParentClass(1)

That should result in JSON something like the following:

{ '__ChildClass__': {
    'bar': 1.1,
    'foo': 'foo',
    'parent': {
        '__ParentClass__': {
            'foo': 1}
        }
    }
}