JSON序列化以元组为键的字典 [英] JSON serialize a dictionary with tuples as key

问题描述

在 Python 中有没有办法序列化使用元组作为键的字典?

Is there a way in Python to serialize a dictionary that is using a tuple as key?

例如

a = {(1, 2): 'a'}

只需使用 json.dumps(a) 就会引发此错误:

simply using json.dumps(a) raises this error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.6/json/__init__.py", line 230, in dumps
    return _default_encoder.encode(obj)
  File "/usr/lib/python2.6/json/encoder.py", line 367, in encode
    chunks = list(self.iterencode(o))
  File "/usr/lib/python2.6/json/encoder.py", line 309, in _iterencode
    for chunk in self._iterencode_dict(o, markers):
  File "/usr/lib/python2.6/json/encoder.py", line 268, in _iterencode_dict
    raise TypeError("key {0!r} is not a string".format(key))
TypeError: key (1, 2) is not a string

推荐答案

你不能将它序列化为 json，json 对于什么是 dict 键的理解远不如 python 灵活.

You can't serialize that as json, json has a much less flexible idea about what counts as a dict key than python.

您可以将映射转换为一系列键值对，如下所示:

You could transform the mapping into a sequence of key, value pairs, something like this:

import json
def remap_keys(mapping):
    return [{'key':k, 'value': v} for k, v in mapping.iteritems()]
... 
json.dumps(remap_keys({(1, 2): 'foo'}))
>>> '[{"value": "foo", "key": [1, 2]}]'

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