通過屬性遞歸訪問字典以及索引訪問？

我希望能夠做這樣的事情：通過屬性遞歸訪問字典以及索引訪問？

from dotDict import dotdictify 

life = {'bigBang': 
      {'stars': 
       {'planets': []} 
      } 
     } 

dotdictify(life) 

# This would be the regular way: 
life['bigBang']['stars']['planets'] = {'earth': {'singleCellLife': {}}} 
# But how can we make this work? 
life.bigBang.stars.planets.earth = {'singleCellLife': {}} 

#Also creating new child objects if none exist, using the following syntax: 
life.bigBang.stars.planets.earth.multiCellLife = {'reptiles':{},'mammals':{}}

我的動機是提高代碼的簡潔，如果可能使用類似的語法爲Javascript訪問JSON對象進行有效的跨平臺開發。（我也用Py2JS和類似。）

來源

2010-06-13 Luke Stanley

'life.bigBang.stars.planets'定義一個'list'，所以分配給它的'.earth'屬性將導致一個'AttributeError：'列表'對象沒有屬性'地球'。我猜你可能想要在'life'字典的定義中使用'{'planets'：{}}''（如接受的答案所示）。 – martineau 2017-10-17 19:29:03

這裏有一個方法來創建這樣的經歷：

class DotDictify(dict): 
    MARKER = object() 

    def __init__(self, value=None): 
     if value is None: 
      pass 
     elif isinstance(value, dict): 
      for key in value: 
       self.__setitem__(key, value[key]) 
     else: 
      raise TypeError('expected dict') 

    def __setitem__(self, key, value): 
     if isinstance(value, dict) and not isinstance(value, DotDictify): 
      value = DotDictify(value) 
     super(DotDictify, self).__setitem__(key, value) 

    def __getitem__(self, key): 
     found = self.get(key, DotDictify.MARKER) 
     if found is DotDictify.MARKER: 
      found = DotDictify() 
      super(DotDictify, self).__setitem__(key, found) 
     return found 

    __setattr__, __getattr__ = __setitem__, __getitem__ 


if __name__ == '__main__': 

    life = {'bigBang': 
       {'stars': 
        {'planets': {} # Value changed from [] 
        } 
       } 
      } 

    life = DotDictify(life) 
    print(life.bigBang.stars.planets) # -> [] 
    life.bigBang.stars.planets.earth = {'singleCellLife' : {}} 
    print(life.bigBang.stars.planets) # -> {'earth': {'singleCellLife': {}}}

來源

2010-06-13 06:08:30

調用字典.__ setitem __（self，key，value）是我失蹤的遞歸技巧！代碼中有相當優雅的代碼:) – 2010-06-13 06:39:50

你（和@Luke）應該使用'super（dotdictify，self）.__ setitem __（key，value）'而不是'dict .__ setitem __（self，key，value）'（否則你的子類有多個祖先會遇到麻煩）。（除了builtins）類應該以大寫字母開頭 – 2014-06-20 09:44:42

@TobiasKienzler感謝您指出邊緣案例 – 2014-06-20 14:56:27

下面的嵌套屬性字典（由柯特Hagenlocher的答案靈感的另一個實現剝離下來基本）：

class AttrDict(dict): 
    """ Nested Attribute Dictionary 

    A class to convert a nested Dictionary into an object with key-values 
    accessibly using attribute notation (AttrDict.attribute) in addition to 
    key notation (Dict["key"]). This class recursively sets Dicts to objects, 
    allowing you to recurse down nested dicts (like: AttrDict.attr.attr) 
    """ 

    def __init__(self, mapping): 
     super(AttrDict, self).__init__() 
     for key, value in mapping.items(): 
      self.__setitem__(key, value) 

    def __setitem__(self, key, value): 
     if isinstance(value, dict): 
      value = AttrDict(value) 
     super(AttrDict, self).__setitem__(key, value) 

    def __getattr__(self, item): 
     try: 
      return self.__getitem__(item) 
     except KeyError: 
      raise AttributeError(item) 

    __setattr__ = __setitem__

這個工作在兩個Python 2和3：

life = AttrDict({'bigBang': {'stars': {'planets': {}}}}) 
life['bigBang']['stars']['planets'] = {'earth': {'singleCellLife': {}}} 
life.bigBang.stars.planets.earth.multiCellLife = {'reptiles': {}, 'mammals': {}} 
print(life.bigBang.stars.planets.earth) 
# -> {'singleCellLife': {}, 'multiCellLife': {'mammals': {}, 'reptiles': {}}}

轉換成KeyError異常在AttributeError的在__getattr__ Python3需要使得hasattr作品也萬一屬性中沒有找到：

hasattr(life, 'parallelUniverse') 
# --> False

來源

2018-02-15 11:52:01 kadee

通過屬性遞歸訪問字典以及索引訪問？

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