db={"movie":[{_id:1,name:"Robo"}],"review":[{"_id":"a","comment":"Awesome","date":"2020-10-22","movieId":1},{"_id":"b","comment":"Awesome","date":"2020-10-24","movieId":1}]}

db.movie.aggregate([{"$lookup":{"from":"review","let":{mid:"$_id"},"pipeline":[{$sort:{date:-1}},{$limit:1},{$match:{$expr:{$eq:["$$mid","$movieId"]}}}],"as":"review"}}])