解碼json數組為Frozensets

Question

我有一個嵌套的json數組，我想將數組解碼為凍結集而不是列表。

import json
class FrozensetDecoder(json.JSONDecoder): 
    def default(self, obj): 
        print(obj) 
        if isinstance(obj, list): 
            return frozenset(obj) 
        return obj 
    array = list = default 


In [8]: json.loads('[1,[2],3]', cls=FrozensetDecoder)                                                                                                                                                                                                                                                  
Out[8]: [1, [2], 3]

但我想要

frozenset({1, frozenset({2}), 3})

Answer 1

我不熟悉您通過重新定義array和list作為default功能所采用的方法。

這是一些可以滿足您需求的代碼：

import json
from json import scanner


class MyDecoder(json.JSONDecoder):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        # set up an alternative function for parsing arrays
        self.previous_parse_array = self.parse_array
        self.parse_array = self.json_array_frozenset
        # ensure that the replaced function gets used
        self.scan_once = scanner.py_make_scanner(self)

    def json_array_frozenset(self, s_and_end, scan_once, **kwargs):
        # call the parse_array that would have been used previously
        values, end = self.previous_parse_array(s_and_end, scan_once, **kwargs)
        # return the same result, but turn the `values` into a frozenset
        return frozenset(values), end


data = json.loads('[1,[2],3]', cls=MyDecoder)
print(data)

請注意，結果將是frozenset({1, 3, frozenset({2})})而不是frozenset({1, frozenset({2}), 3})但是由於集合是無序的，所以沒關系。