带有元组键的 msgpack 字典

问题描述

import msgpack
path = 'test.msgpack'
with open(path,"wb") as outfile:
    outfile.write(msgpack.packb({ (1,2): 'str' }))

工作正常，现在

with open(path,'rb') as infile:
    print(msgpack.unpackb(infile.read()))

错误

Traceback (most recent call last):
  File "<stdin>",line 2,in <module>
  File "msgpack/_unpacker.pyx",line 195,in msgpack._cmsgpack.unpackb
ValueError: list is not allowed for map key

（只有在解包时才检测到错误是不是很奇怪？）

如何编写或解决将元组作为键的 python dict msgpacking 的方法？

解决方法

这里有两个问题：msgpack 默认使用 strict_map_key=True，因为版本 1.0.0 (source) 和 msgpack 的数组被隐式转换为 Python 的lists - 不可散列。为了使事情工作，传递所需的关键字参数：

with open(path,"rb") as f:
    print(msgpack.unpackb(f.read(),use_list=False,strict_map_key=False))

# outputs: {(1,2): 'str'}