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
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'
其他回答
>>> def dict2obj(d):
if isinstance(d, list):
d = [dict2obj(x) for x in d]
if not isinstance(d, dict):
return d
class C(object):
pass
o = C()
for k in d:
o.__dict__[k] = dict2obj(d[k])
return o
>>> d = {'a': 1, 'b': {'c': 2}, 'd': ["hi", {'foo': "bar"}]}
>>> x = dict2obj(d)
>>> x.a
1
>>> x.b.c
2
>>> x.d[1].foo
'bar'
我有一些__getattr__没有被调用的问题，所以我构造了一个新的样式类版本:
class Struct(object):
'''The recursive class for building and representing objects with.'''
class NoneStruct(object):
def __getattribute__(*args):
return Struct.NoneStruct()
def __eq__(self, obj):
return obj == None
def __init__(self, obj):
for k, v in obj.iteritems():
if isinstance(v, dict):
setattr(self, k, Struct(v))
else:
setattr(self, k, v)
def __getattribute__(*args):
try:
return object.__getattribute__(*args)
except:
return Struct.NoneStruct()
def __repr__(self):
return '{%s}' % str(', '.join('%s : %s' % (k, repr(v)) for
(k, v) in self.__dict__.iteritems()))
该版本还增加了一个NoneStruct，当未设置的属性被调用时返回。这允许使用None测试来查看属性是否存在。非常有用时，确切的字典输入是不知道的(设置等)。
bla = Struct({'a':{'b':1}})
print(bla.a.b)
>> 1
print(bla.a.c == None)
>> True
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'
让我来解释一下不久前我几乎用过的一个解决方案。但首先，我没有这样做的原因可以通过以下代码来说明:
d = {'from': 1}
x = dict2obj(d)
print x.from
给出这个错误:
File "test.py", line 20
print x.from == 1
^
SyntaxError: invalid syntax
因为“from”是Python关键字，所以某些字典键是不允许的。
现在我的解决方案允许直接使用字典项的名称来访问它们。但是它也允许你使用“字典语义”。下面是使用示例的代码:
class dict2obj(dict):
def __init__(self, dict_):
super(dict2obj, self).__init__(dict_)
for key in self:
item = self[key]
if isinstance(item, list):
for idx, it in enumerate(item):
if isinstance(it, dict):
item[idx] = dict2obj(it)
elif isinstance(item, dict):
self[key] = dict2obj(item)
def __getattr__(self, key):
return self[key]
d = {'a': 1, 'b': {'c': 2}, 'd': ["hi", {'foo': "bar"}]}
x = dict2obj(d)
assert x.a == x['a'] == 1
assert x.b.c == x['b']['c'] == 2
assert x.d[1].foo == x['d'][1]['foo'] == "bar"
老式问答，但我有更多的话题要谈。似乎没有人谈论递归字典。这是我的代码:
#!/usr/bin/env python
class Object( dict ):
def __init__( self, data = None ):
super( Object, self ).__init__()
if data:
self.__update( data, {} )
def __update( self, data, did ):
dataid = id(data)
did[ dataid ] = self
for k in data:
dkid = id(data[k])
if did.has_key(dkid):
self[k] = did[dkid]
elif isinstance( data[k], Object ):
self[k] = data[k]
elif isinstance( data[k], dict ):
obj = Object()
obj.__update( data[k], did )
self[k] = obj
obj = None
else:
self[k] = data[k]
def __getattr__( self, key ):
return self.get( key, None )
def __setattr__( self, key, value ):
if isinstance(value,dict):
self[key] = Object( value )
else:
self[key] = value
def update( self, *args ):
for obj in args:
for k in obj:
if isinstance(obj[k],dict):
self[k] = Object( obj[k] )
else:
self[k] = obj[k]
return self
def merge( self, *args ):
for obj in args:
for k in obj:
if self.has_key(k):
if isinstance(self[k],list) and isinstance(obj[k],list):
self[k] += obj[k]
elif isinstance(self[k],list):
self[k].append( obj[k] )
elif isinstance(obj[k],list):
self[k] = [self[k]] + obj[k]
elif isinstance(self[k],Object) and isinstance(obj[k],Object):
self[k].merge( obj[k] )
elif isinstance(self[k],Object) and isinstance(obj[k],dict):
self[k].merge( obj[k] )
else:
self[k] = [ self[k], obj[k] ]
else:
if isinstance(obj[k],dict):
self[k] = Object( obj[k] )
else:
self[k] = obj[k]
return self
def test01():
class UObject( Object ):
pass
obj = Object({1:2})
d = {}
d.update({
"a": 1,
"b": {
"c": 2,
"d": [ 3, 4, 5 ],
"e": [ [6,7], (8,9) ],
"self": d,
},
1: 10,
"1": 11,
"obj": obj,
})
x = UObject(d)
assert x.a == x["a"] == 1
assert x.b.c == x["b"]["c"] == 2
assert x.b.d[0] == 3
assert x.b.d[1] == 4
assert x.b.e[0][0] == 6
assert x.b.e[1][0] == 8
assert x[1] == 10
assert x["1"] == 11
assert x[1] != x["1"]
assert id(x) == id(x.b.self.b.self) == id(x.b.self)
assert x.b.self.a == x.b.self.b.self.a == 1
x.x = 12
assert x.x == x["x"] == 12
x.y = {"a":13,"b":[14,15]}
assert x.y.a == 13
assert x.y.b[0] == 14
def test02():
x = Object({
"a": {
"b": 1,
"c": [ 2, 3 ]
},
1: 6,
2: [ 8, 9 ],
3: 11,
})
y = Object({
"a": {
"b": 4,
"c": [ 5 ]
},
1: 7,
2: 10,
3: [ 12 , 13 ],
})
z = {
3: 14,
2: 15,
"a": {
"b": 16,
"c": 17,
}
}
x.merge( y, z )
assert 2 in x.a.c
assert 3 in x.a.c
assert 5 in x.a.c
assert 1 in x.a.b
assert 4 in x.a.b
assert 8 in x[2]
assert 9 in x[2]
assert 10 in x[2]
assert 11 in x[3]
assert 12 in x[3]
assert 13 in x[3]
assert 14 in x[3]
assert 15 in x[2]
assert 16 in x.a.b
assert 17 in x.a.c
if __name__ == '__main__':
test01()
test02()
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