python - 解析 JSON 以查找键的值

Question

我正在尝试解析 json 以找到所需键的值。我递归地这样做。如果有另一种更快或更有效的方法，我愿意接受

示例 json:

{  
   "data_version":"5",
   "application":{  
      "platform":"iPhone",
      "os":"iPhone OS",
      "locale":"en_US",
      "app_version":"unknown",
      "mobile":{  
         "device":"iPhone",
         "carrier":"Verizon",
      }
   },
   "event_header":{  
      "accept_language":"en-us",
      "topic_name":"mobile-clickstream",
      "server_timestamp":1416958459572,
      "version":"1.0"
   },
   "session":{  
      "properties":{  

      }
   },
   "event":{  
      "timestamp":1416958459185,
      "properties":{  
         "event_sequence_number":97
      }
   }
}

这是我目前的情况

def json_scan(json_obj, key):
    result = None
    for element in json_obj:
        if str(element) == key:
            result = json_obj[element]
        else:
            if type(json_obj[element]) == DictType:
                json_scan(json_obj[element], key)
            elif type(json_obj[element]) == ListType:
                json_scan(element, key)
    return result

预期输出:

>>> json_scan(json_obj, "timestamp")
1416958459185

当我通过调试器时，我能够找到所需的值，但是 result = None 行将结果重置为 None 并且在方法的末尾，我得到的值是 None。我不确定如何解决这个问题。我尝试删除该行但出现错误，因为结果未预设为值。

Answer 1

使用 json 库来解析 json 文件(应该删除一些逗号)并使用 native 字典类型:

def json_scan(json_obj, key):
    d = json.loads(json_obj)

    def _(dictobj, lookup):
        if lookup in dictobj.keys():
            return dictobj[lookup]
        else:
            for sub_dictobj in [d for d in dictobj.values() if type(d) == DictType]:
                result = _(sub_dictobj, lookup)
                if result:
                    return result
            return None

    return _(d, key)

更完整的版本:

def json_scan(json_obj, key):
    d = json.loads(json_obj)

    def _(dictobj, lookup):
        if lookup in dictobj.keys():
            return dictobj[lookup]
        else:
            for sub_dictobj in [d for d in dictobj.values() if type(d) == DictType]:
                result = _(sub_dictobj, lookup)
                if result:
                    return result

            # if objects in dictobj.values() are lists, go through them
            for listobject in [l for l in dictobj.values() if type(d) == list]:
                for sub_dictobj in [d for d in listobject if type(d) == DictType]:
                    result = _(sub_dictobj, lookup)
                    if result:
                        return result
            return None

    return _(d, key)

编辑(2015/04/25):

看完 @PyCon 2015 视频后，我遇到了 dict_digger :

http://jtushman.github.io/blog/2013/11/06/dict-digger/ https://github.com/jtushman/dict_digger

它带有测试...