https://pypi.python.org/pypi/dictsearch/
Has query and search functions for "nested dictionaries", where these nested structures contain dictionaries, lists, and other objects (that are treated as values).
This package was motivated after calling simplejson on objects returned from Twitter API calls. The API objects I had to parse had quadruple level nested dictionaries, but sometimes an entire inner dictionary or level would be missing. Trying to query level 4 when level 1 2 or 3 does not exist bombs with a key error instead of just returning None; nothing in the Python language natively supports querying nested dicts when they may or may not exist: http://stackoverflow.com/questions/26979046/python-check-multi-level-dict-key-existence
See test_search.py for more.
from dictsearch.search import iterate_dictionary
d = dict()
d["A"] = dict()
d["A"]["B"] = []
d["A"]["B"].append(dict())
d["A"]["B"][0]["C"] = 123
d["A"]["B"].append(dict())
d["A"]["B"][1]["C"] = 123
d["A"]["B"].append(dict())
d["A"]["B"][2]["D"] = dict()
d["A"]["B"][2]["D"]["E"] = "ASDF"
print(d)
print(iterate_dictionary(d,"X/Y/Z"))
print(iterate_dictionary(d,"A"))
print(iterate_dictionary(d,"A/B"))
print(iterate_dictionary(d,"A/C"))
print(iterate_dictionary(d,"A/B/C"))
print(iterate_dictionary(d,"A/B/C/D")) #DOES NOT EXIST; D NOT AFTER PATH "C"
print(iterate_dictionary(d,"A/B/D/E"))
print(iterate_dictionary(d,"A/B/E")) #DOES NOT EXIST; E NOT A SUBPATH OF "B"
>>
{'A': {'B': [{'C': 123}, {'C': 123}, {'D': {'E': 'ASDF'}}]}}
None
[{'B': [{'C': 123}, {'C': 123}, {'D': {'E': 'ASDF'}}]}]
[{'C': 123}, {'C': 123}, {'D': {'E': 'ASDF'}}]
None
[123, 123]
None
['ASDF']
None