从Python 3.4开始，你可以使用suppress (KeyError)来访问嵌套的json对象，而不用担心KeyError

from contextlib import suppress

with suppress(KeyError):
    a1 = json_obj['key1']['key2']['key3']
    a2 = json_obj['key4']['key5']['key6']
    a3 = json_obj['key7']['key8']['key9']

Techdragon提供。看看他的回答，了解更多细节:https://stackoverflow.com/a/45874251/1189659

对于嵌套的字典/JSON查找，可以使用dictor

PIP安装指示器

dict对象

{
    "characters": {
        "Lonestar": {
            "id": 55923,
            "role": "renegade",
            "items": [
                "space winnebago",
                "leather jacket"
            ]
        },
        "Barfolomew": {
            "id": 55924,
            "role": "mawg",
            "items": [
                "peanut butter jar",
                "waggy tail"
            ]
        },
        "Dark Helmet": {
            "id": 99999,
            "role": "Good is dumb",
            "items": [
                "Shwartz",
                "helmet"
            ]
        },
        "Skroob": {
            "id": 12345,
            "role": "Spaceballs CEO",
            "items": [
                "luggage"
            ]
        }
    }
}

要获得龙星的物品，只需提供一个点分隔的路径，即

import json
from dictor import dictor

with open('test.json') as data: 
    data = json.load(data)

print dictor(data, 'characters.Lonestar.items')

>> [u'space winnebago', u'leather jacket']

如果键不在路径中，您可以提供回退值

你还有很多选择，比如忽略字母大小写，使用'以外的其他字符。作为路径分隔符，

https://github.com/perfecto25/dictor

根据Yoav的回答，一个更安全的方法是:

def deep_get(dictionary, *keys):
    return reduce(lambda d, key: d.get(key, None) if isinstance(d, dict) else None, keys, dictionary)

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)

通过把所有这些答案和我做的小改变结合起来，我认为这个函数会很有用。安全、快捷、易于维护。

def deep_get(dictionary, keys, default=None):
    return reduce(lambda d, key: d.get(key, default) if isinstance(d, dict) else default, keys.split("."), dictionary)

例子:

from functools import reduce
def deep_get(dictionary, keys, default=None):
    return reduce(lambda d, key: d.get(key, default) if isinstance(d, dict) else default, keys.split("."), dictionary)

person = {'person':{'name':{'first':'John'}}}
print(deep_get(person, "person.name.first"))    # John

print(deep_get(person, "person.name.lastname")) # None

print(deep_get(person, "person.name.lastname", default="No lastname"))  # No lastname