我没有看到这里提到串行版本或backcompat，所以我将发布我的解决方案，我已经使用了一点。我可能还有很多东西要学习，特别是Java和Javascript可能比我更成熟，但我要这样做

https://gist.github.com/andy-d/b7878d0044a4242c0498ed6d67fd50fe

除了Onur的答案，你可能想要处理如下的datetime类型。(以便处理:'datetime. time.)Datetime对象没有属性dict异常。)

def datetime_option(value):
    if isinstance(value, datetime.date):
        return value.timestamp()
    else:
        return value.__dict__

用法:

def toJSON(self):
    return json.dumps(self, default=datetime_option, sort_keys=True, indent=4)

基于Quinten Cabo的回答:

def sterilize(obj):
    """Make an object more ameniable to dumping as json
    """
    if type(obj) in (str, float, int, bool, type(None)):
        return obj
    elif isinstance(obj, dict):
        return {k: sterilize(v) for k, v in obj.items()}
    list_ret = []
    dict_ret = {}
    for a in dir(obj):
        if a == '__iter__' and callable(obj.__iter__):
            list_ret.extend([sterilize(v) for v in obj])
        elif a == '__dict__':
            dict_ret.update({k: sterilize(v) for k, v in obj.__dict__.items() if k not in ['__module__', '__dict__', '__weakref__', '__doc__']})
        elif a not in ['__doc__', '__module__']:
            aval = getattr(obj, a)
            if type(aval) in (str, float, int, bool, type(None)):
                dict_ret[a] = aval
            elif a != '__class__' and a != '__objclass__' and isinstance(aval, type):
                dict_ret[a] = sterilize(aval)
    if len(list_ret) == 0:
        if len(dict_ret) == 0:
            return repr(obj)
        return dict_ret
    else:
        if len(dict_ret) == 0:
            return list_ret
    return (list_ret, dict_ret)

区别在于

Works for any iterable instead of just list and tuple (it works for NumPy arrays, etc.) Works for dynamic types (ones that contain a __dict__). Includes native types float and None so they don't get converted to string. Classes that have __dict__ and members will mostly work (if the __dict__ and member names collide, you will only get one - likely the member) Classes that are lists and have members will look like a tuple of the list and a dictionary Python3 (that isinstance() call may be the only thing that needs changing)

为了给这场11年的大火再添一根柴，我想要一个满足以下条件的解决方案:

只允许使用json.dumps(obj)序列化类FileItem的实例 允许FileItem实例具有属性:FileItem .fname 允许FileItem实例提供给任何库，使用json.dumps(obj)序列化它 不需要将任何其他字段传递给json。转储(如自定义序列化器)

IE:

fileItem = FileItem('filename.ext')
assert json.dumps(fileItem) == '{"fname": "filename.ext"}'
assert fileItem.fname == 'filename.ext'

我的解决方案是:

obj的类是否继承自dict 将每个对象属性映射到底层字典

class FileItem(dict):
    def __init__(self, fname):
        self['fname'] = fname

    #fname property
    fname: str = property()
    @fname.getter
    def fname(self):
        return self['fname']

    @fname.setter
    def fname(self, value: str):
        self['fname'] = value

    #Repeat for other properties

是的，如果你有很多属性，这有点冗长，但它是JSONSerializable，它的行为像一个对象，你可以把它给任何库，去json.dumps(obj)它。

另一种选择是将JSON转储打包到它自己的类中:

import json

class FileItem:
    def __init__(self, fname):
        self.fname = fname

    def __repr__(self):
        return json.dumps(self.__dict__)

或者，更好的是，从JsonSerializable类继承FileItem类:

import json

class JsonSerializable(object):
    def toJson(self):
        return json.dumps(self.__dict__)

    def __repr__(self):
        return self.toJson()


class FileItem(JsonSerializable):
    def __init__(self, fname):
        self.fname = fname

测试:

>>> f = FileItem('/foo/bar')
>>> f.toJson()
'{"fname": "/foo/bar"}'
>>> f
'{"fname": "/foo/bar"}'
>>> str(f) # string coercion
'{"fname": "/foo/bar"}'

只需要像这样添加to_json方法到你的类中:

def to_json(self):
  return self.message # or how you want it to be serialized

然后将这段代码(来自这个答案)添加到所有内容的顶部:

from json import JSONEncoder

def _default(self, obj):
    return getattr(obj.__class__, "to_json", _default.default)(obj)

_default.default = JSONEncoder().default
JSONEncoder.default = _default

这将会在导入json模块时monkey-patch，所以 JSONEncoder.default()自动检查特殊的to_json() 方法，并使用它对找到的对象进行编码。

就像Onur说的，但是这次你不需要更新项目中的每个json.dumps()。