Safe method to get value of nested dictionary

You could use get twice:

example_dict.get('key1', {}).get('key2')

This will return None if either key1 or key2 does not exist.

Note that this could still raise an AttributeError if example_dict['key1'] exists but is not a dict (or a dict-like object with a get method). The try..except code you posted would raise a TypeError instead if example_dict['key1'] is unsubscriptable.

Another difference is that the try...except short-circuits immediately after the first missing key. The chain of get calls does not.

If you wish to preserve the syntax, example_dict['key1']['key2'] but do not want it to ever raise KeyErrors, then you could use the Hasher recipe:

class Hasher(dict):    # https://stackoverflow.com/a/3405143/190597    def __missing__(self, key):        value = self[key] = type(self)()        return valueexample_dict = Hasher()print(example_dict['key1'])# {}print(example_dict['key1']['key2'])# {}print(type(example_dict['key1']['key2']))# <class '__main__.Hasher'>

Note that this returns an empty Hasher when a key is missing.

Since Hasher is a subclass of dict you can use a Hasher in much the same way you could use a dict. All the same methods and syntax is available, Hashers just treat missing keys differently.

You can convert a regular dict into a Hasher like this:

hasher = Hasher(example_dict)

and convert a Hasher to a regular dict just as easily:

regular_dict = dict(hasher)

Another alternative is to hide the ugliness in a helper function:

def safeget(dct, *keys):    for key in keys:        try:            dct = dct[key]        except KeyError:            return None    return dct

So the rest of your code can stay relatively readable:

safeget(example_dict, 'key1', 'key2')

You could also use python reduce:

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

By combining all of these answer here and small changes that I made, I think this function would be useful. its safe, quick, easily maintainable.

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)

Example :

>>> 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>>>