Aggregate MongoDB results by ObjectId date

Question

How can I aggregate my MongoDB results by ObjectId date. Example:

Default cursor results:

cursor = [
    {\'_id\': ObjectId(\'5220b974a61ad0000746c0d         


        

Answer 1

So this doesn't answer my question directly, but I did find a better way to replace all that lambda nonsense above using Python's setdefault:

d = {}
for message in messages:
    key = message['_id'].generation_time.date()
    d.setdefault(key,[]).append(message)

Thanks to @raymondh for the hint in is PyCon talk:

Transforming Code into Beautiful, Idiomatic Python