如果您想使用另一个库来解决问题，这是最好的方法

https://github.com/maztohir/dict-path

from dict-path import DictPath

data_dict = {
  "foo1": "bar1",
  "foo2": "bar2",
  "foo3": {
     "foo4": "bar4",
     "foo5": {
        "foo6": "bar6",
        "foo7": "bar7",
     },
  }
}

data_dict_path = DictPath(data_dict)
data_dict_path.get('key1/key2/key3')

在深入获取属性后，我使用点表示法安全地获得嵌套的dict值。这适用于我，因为我的字典是反序列化的MongoDB对象，所以我知道键名不包含.s。此外，在我的上下文中，我可以指定一个数据中没有的虚假回退值(None)，因此在调用函数时可以避免使用try/except模式。

from functools import reduce # Python 3
def deepgetitem(obj, item, fallback=None):
    """Steps through an item chain to get the ultimate value.

    If ultimate value or path to value does not exist, does not raise
    an exception and instead returns `fallback`.

    >>> d = {'snl_final': {'about': {'_icsd': {'icsd_id': 1}}}}
    >>> deepgetitem(d, 'snl_final.about._icsd.icsd_id')
    1
    >>> deepgetitem(d, 'snl_final.about._sandbox.sbx_id')
    >>>
    """
    def getitem(obj, name):
        try:
            return obj[name]
        except (KeyError, TypeError):
            return fallback
    return reduce(getitem, item.split('.'), obj)

如果您想使用另一个库来解决问题，这是最好的方法

https://github.com/maztohir/dict-path

from dict-path import DictPath

data_dict = {
  "foo1": "bar1",
  "foo2": "bar2",
  "foo3": {
     "foo4": "bar4",
     "foo5": {
        "foo6": "bar6",
        "foo7": "bar7",
     },
  }
}

data_dict_path = DictPath(data_dict)
data_dict_path.get('key1/key2/key3')

已经有很多很好的答案，但我已经提出了一个类似于JavaScript领域的lodash get的函数，它也支持通过索引进入列表:

def get(value, keys, default_value = None):
'''
    Useful for reaching into nested JSON like data
    Inspired by JavaScript lodash get and Clojure get-in etc.
'''
  if value is None or keys is None:
      return None
  path = keys.split('.') if isinstance(keys, str) else keys
  result = value
  def valid_index(key):
      return re.match('^([1-9][0-9]*|[0-9])$', key) and int(key) >= 0
  def is_dict_like(v):
      return hasattr(v, '__getitem__') and hasattr(v, '__contains__')
  for key in path:
      if isinstance(result, list) and valid_index(key) and int(key) < len(result):
          result = result[int(key)] if int(key) < len(result) else None
      elif is_dict_like(result) and key in result:
          result = result[key]
      else:
          result = default_value
          break
  return result

def test_get():
  assert get(None, ['foo']) == None
  assert get({'foo': 1}, None) == None
  assert get(None, None) == None
  assert get({'foo': 1}, []) == {'foo': 1}
  assert get({'foo': 1}, ['foo']) == 1
  assert get({'foo': 1}, ['bar']) == None
  assert get({'foo': 1}, ['bar'], 'the default') == 'the default'
  assert get({'foo': {'bar': 'hello'}}, ['foo', 'bar']) == 'hello'
  assert get({'foo': {'bar': 'hello'}}, 'foo.bar') == 'hello'
  assert get({'foo': [{'bar': 'hello'}]}, 'foo.0.bar') == 'hello'
  assert get({'foo': [{'bar': 'hello'}]}, 'foo.1') == None
  assert get({'foo': [{'bar': 'hello'}]}, 'foo.1.bar') == None
  assert get(['foo', 'bar'], '1') == 'bar'
  assert get(['foo', 'bar'], '2') == None

Glom是一个很好的库，可以进入点查询:

In [1]: from glom import glom

In [2]: data = {'a': {'b': {'c': 'd'}}}

In [3]: glom(data, "a.b.c")
Out[3]: 'd'

查询失败有一个很好的堆栈跟踪，指出确切的故障点:

In [4]: glom(data, "a.b.foo")
---------------------------------------------------------------------------
PathAccessError                           Traceback (most recent call last)
<ipython-input-4-2a3467493ac4> in <module>
----> 1 glom(data, "a.b.foo")

~/.cache/pypoetry/virtualenvs/neural-knapsack-dE7ihQtM-py3.8/lib/python3.8/site-packages/glom/core.py in glom(target, spec, **kwargs)
   2179 
   2180     if err:
-> 2181         raise err
   2182     return ret
   2183 

PathAccessError: error raised while processing, details below.
 Target-spec trace (most recent last):
 - Target: {'a': {'b': {'c': 'd'}}}
 - Spec: 'a.b.foo'
glom.core.PathAccessError: could not access 'foo', part 2 of Path('a', 'b', 'foo'), got error: KeyError('foo')

默认保护:

In [5]: glom(data, "a.b.foo", default="spam")
Out[5]: 'spam'

格洛姆的魅力在于多功能的规格参数。例如，可以很容易地从以下数据中提取所有的名字:

In [8]: data = {
   ...:     "people": [
   ...:         {"first_name": "Alice", "last_name": "Adams"},
   ...:         {"first_name": "Bob", "last_name": "Barker"}
   ...:     ]
   ...: }

In [9]: glom(data, ("people", ["first_name"]))
Out[9]: ['Alice', 'Bob']

更多的例子请阅读glom文档。

对于二级键检索，你可以这样做:

key2_value = (example_dict.get('key1') or {}).get('key2')