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

The answer to this question maybe help.

db.collection_name.aggregate({
    "$match": {
        "complist": {
            "$elemMatch": {
                "a": "a"
            }
        }
    }
});