How to check if a key exists in an inner dictionary inside a dictionary in python?

Question

There is a python dictionary:

a = {b:{c:{\"x\":1, \"y\":2, \"z\":3}}}

I want to know if a[b][c][\"z\"] exists, but yet I don\'t kn

Answer 1

Why don't you use your own function, it gives you flexibility, Recursion!

def _finditem(obj, key):
    if key in obj: return obj[key]
    for k, v in obj.items():
        if isinstance(v,dict):
            item = _finditem(v, key)
            if item is not None:
                return item

Of course, that will fail if you have None values in any of your dictionaries. In that case, you could set up a sentinel object() for this function and return that in the case that you don't find anything -- Then you can check against the sentinel to know if you found something or not.