looks like you need to search the documents
collection on a level deeper.
As of now you search for the element
And the $in operator of your documents
collection compares it to the list elements such
which obviously aren't the same ever.
Unfortunately I don't have a mongodb to test any
but maybe that tip helps you a little to improve
Found an older question here
regarding a similar problem maybe that'll helps.
According to that post something like the
for page in