How to query in the nested array.(using pymongo)?

It looks like you're embedding topics as an array all in a single document. You should try to avoid returning partial documents frequently from MongoDB. You can do it with the "fields" argument of the find method, but it isn't very easy to work with if you're doing it frequently.

MongoDB operates on documents, that is, the top level documents (the things you save, update, insert, find, and find_one on). Mongo's query language lets you search within embedded objects, but will always return, update, or manipulate one (or more) of these top-level documents.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.