dictionary - Chained, nested dict() get calls in python

Question

I'm interrogating a nested dictionary using the dict.get('keyword') method. Currently my syntax is...

M = cursor_object_results_of_db_query

for m in M:
    X = m.get("gparents").get("parent").get("child")
    for x in X:
        y = x.get("key")

However, sometimes one of the "parent" or "child" tags doesn't exist, and my script fails. I know using get() I can include a default in the case the key doesn't exist of the form...

get("parent", '') or
get("parent", 'orphan') 

But if I include any Null, '', or empty I can think of, the chained .get("child") fails when called on ''.get("child") since "" has no method .get().

The way I'm solving this now is by using a bunch of sequential try-except around each .get("") call, but that seems foolish and unpython---is there a way to default return "skip" or "pass" or something that would still support chaining and fail intelligently, rather than deep-dive into keys that don't exist?

Ideally, I'd like this to be a list comprehension of the form:

[m.get("gparents").get("parent").get("child") for m in M]

but this is currently impossible when an absent parent causes the .get("child") call to terminate my program.

Answer 1

Since these are all python dicts and you are calling the dict.get() method on them, you can use an empty dict to chain:

[m.get("gparents", {}).get("parent", {}).get("child") for m in M]

By leaving off the default for the last .get() you fall back to None. Now, if any of the intermediary keys is not found, the rest of the chain will use empty dictionaries to look things up, terminating in .get('child') returning None.