How to use $elemMatch on aggregate's projection?

Question

This is my object:

{ \"_id\" : ObjectId(\"53fdcb6796cb9b9aa86f05b9\"), \"list\" : [ \"a\", \"b\" ], \"complist\" : [ { \"a\" : \"a\", \"b\" : \"b\" }, { \"a\         


        

Answer 1

Actually, the simplest solution is to just $unwind your array, then $match the appropriate documents. You can wind-up the appropriate documents again using $group and $push.