[Python-ideas] Json object-level serializer

Georg Brandl g.brandl at gmx.net
Thu Jul 29 15:12:54 CEST 2010

Am 29.07.2010 14:31, schrieb M.-A. Lemburg:
> Georg Brandl wrote:
>> Am 29.07.2010 13:35, schrieb Tarek Ziadé:
>>> Hello,
>>> What about adding in the json package the ability for an object to
>>> provide a different object to serialize ?
>>> This would be useful to translate a class into a structure that can be
>>> passed to json.dumps
>>> So, it __json__ is provided, its used for serialization instead of the
>>> object itself:
>>>>>> import json
>>>>>> class MyComplexClass(object):
>>> ....     def __json__(self):
>>> ....         return 'json'
>>> ....
>>>>>> o = MyComplexClass()
>>>>>> json.dumps(o)
>>> '"json"'
>> You can do this with a very short subclass of the JSONEncoder:
>> class MyJSONEncoder(JSONEncoder):
>>     def default(self, obj):
>>         return obj.__json__()  # with a useful failure message
> Does that also work with the JSON C extension ?

I think so.  The C encoder gets the default function as an argument.


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