db={"quiz":[{"_id":1,"chat":[{"question":{"id":"1234","message":"First Question","date":"2024-09-30T20:37:44.653Z"},"answer":{"id":"abc","message":"First Question","date":"2024-09-30T20:37:44.653Z"}},{"question":{"id":"1234","message":"First Question","date":"2024-09-30T20:37:44.653Z"}/** <-------- Add answer object to here*/}]},{"_id":2,"chat":[{"question":{"id":"1234","message":"First Question","date":"2024-09-30T20:37:44.653Z"},"answer":{"id":"abc","message":"First Question","date":"2024-09-30T20:37:44.653Z"}},{"question":{"id":"1234","message":"First Question","date":"2024-09-30T20:37:44.653Z"},"answer":{"result":"failure"}}]}],"meta":[{"by":"steevej","at":"gmail"}]}

db.quiz.update({chat:{$elemMatch:{"question":{$type:"object"},"answer":null}}},{$set:{"chat.$.answer":6174}})