我正在寻找一种优雅的方式来获得数据使用属性访问字典与一些嵌套的字典和列表(即javascript风格的对象语法)。
例如:
>>> d = {'a': 1, 'b': {'c': 2}, 'd': ["hi", {'foo': "bar"}]}
应该以这样的方式访问:
>>> x = dict2obj(d)
>>> x.a
1
>>> x.b.c
2
>>> x.d[1].foo
bar
我想,如果没有递归,这是不可能的,但是有什么更好的方法来获得字典的对象样式呢?
我正在寻找一种优雅的方式来获得数据使用属性访问字典与一些嵌套的字典和列表(即javascript风格的对象语法)。
例如:
>>> d = {'a': 1, 'b': {'c': 2}, 'd': ["hi", {'foo': "bar"}]}
应该以这样的方式访问:
>>> x = dict2obj(d)
>>> x.a
1
>>> x.b.c
2
>>> x.d[1].foo
bar
我想,如果没有递归,这是不可能的,但是有什么更好的方法来获得字典的对象样式呢?
当前回答
# Applies to Python-3 Standard Library
class Struct(object):
def __init__(self, data):
for name, value in data.items():
setattr(self, name, self._wrap(value))
def _wrap(self, value):
if isinstance(value, (tuple, list, set, frozenset)):
return type(value)([self._wrap(v) for v in value])
else:
return Struct(value) if isinstance(value, dict) else value
# Applies to Python-2 Standard Library
class Struct(object):
def __init__(self, data):
for name, value in data.iteritems():
setattr(self, name, self._wrap(value))
def _wrap(self, value):
if isinstance(value, (tuple, list, set, frozenset)):
return type(value)([self._wrap(v) for v in value])
else:
return Struct(value) if isinstance(value, dict) else value
可以用于任何深度的任何序列/字典/值结构。
其他回答
下面是一个使用namedtuple的嵌套就绪版本:
from collections import namedtuple
class Struct(object):
def __new__(cls, data):
if isinstance(data, dict):
return namedtuple(
'Struct', data.iterkeys()
)(
*(Struct(val) for val in data.values())
)
elif isinstance(data, (tuple, list, set, frozenset)):
return type(data)(Struct(_) for _ in data)
else:
return data
=>
>>> d = {'a': 1, 'b': {'c': 2}, 'd': ["hi", {'foo': "bar"}]}
>>> s = Struct(d)
>>> s.d
['hi', Struct(foo='bar')]
>>> s.d[0]
'hi'
>>> s.d[1].foo
'bar'
在@max-sirwa的代码上更新了递归数组展开
class Objectify:
def __init__(self, **kwargs):
for key, value in kwargs.items():
if isinstance(value, dict):
f = Objectify(**value)
self.__dict__.update({key: f})
elif isinstance(value, list):
t = []
for i in value:
t.append(Objectify(**i)) if isinstance(i, dict) else t.append(i)
self.__dict__.update({key: t})
else:
self.__dict__.update({key: value})
x = type('new_dict', (object,), d)
然后再加上递归,就完成了。
编辑这是我如何实现它:
>>> d
{'a': 1, 'b': {'c': 2}, 'd': ['hi', {'foo': 'bar'}]}
>>> def obj_dic(d):
top = type('new', (object,), d)
seqs = tuple, list, set, frozenset
for i, j in d.items():
if isinstance(j, dict):
setattr(top, i, obj_dic(j))
elif isinstance(j, seqs):
setattr(top, i,
type(j)(obj_dic(sj) if isinstance(sj, dict) else sj for sj in j))
else:
setattr(top, i, j)
return top
>>> x = obj_dic(d)
>>> x.a
1
>>> x.b.c
2
>>> x.d[1].foo
'bar'
将字典转换为对象
from types import SimpleNamespace
def dict2obj(data):
"""将字典对象转换为可访问的对象属性"""
if not isinstance(data, dict):
raise ValueError('data must be dict object.')
def _d2o(d):
_d = {}
for key, item in d.items():
if isinstance(item, dict):
_d[key] = _d2o(item)
else:
_d[key] = item
return SimpleNamespace(**_d)
return _d2o(data)
参考答案
I ended up trying BOTH the AttrDict and the Bunch libraries and found them to be way too slow for my uses. After a friend and I looked into it, we found that the main method for writing these libraries results in the library aggressively recursing through a nested object and making copies of the dictionary object throughout. With this in mind, we made two key changes. 1) We made attributes lazy-loaded 2) instead of creating copies of a dictionary object, we create copies of a light-weight proxy object. This is the final implementation. The performance increase of using this code is incredible. When using AttrDict or Bunch, these two libraries alone consumed 1/2 and 1/3 respectively of my request time(what!?). This code reduced that time to almost nothing(somewhere in the range of 0.5ms). This of course depends on your needs, but if you are using this functionality quite a bit in your code, definitely go with something simple like this.
class DictProxy(object):
def __init__(self, obj):
self.obj = obj
def __getitem__(self, key):
return wrap(self.obj[key])
def __getattr__(self, key):
try:
return wrap(getattr(self.obj, key))
except AttributeError:
try:
return self[key]
except KeyError:
raise AttributeError(key)
# you probably also want to proxy important list properties along like
# items(), iteritems() and __len__
class ListProxy(object):
def __init__(self, obj):
self.obj = obj
def __getitem__(self, key):
return wrap(self.obj[key])
# you probably also want to proxy important list properties along like
# __iter__ and __len__
def wrap(value):
if isinstance(value, dict):
return DictProxy(value)
if isinstance(value, (tuple, list)):
return ListProxy(value)
return value
参见https://stackoverflow.com/users/704327/michael-merickel的原始实现。
另一件需要注意的事情是,这个实现非常简单,并且没有实现您可能需要的所有方法。您需要根据需要在DictProxy或ListProxy对象上写入这些内容。