Database
db={"userinfo":[{"_id":ObjectId("56d82612b63f1c31cf906003"),"userId":"AD","phone":"0000000000"}],"userrole":[{"_id":ObjectId("56d82612b63f1c31cf906003"),"userId":"AD","role":"admin"}],"users":[{"_id":ObjectId("5684f3c454b1fd6926c324fd"),"email":"admin@gmail.com","userId":"AD","userName":"admin"}]}
Query
db.userinfo.aggregate([{"$lookup":{"from":"userrole","localField":"userId","foreignField":"userId","as":"roleJoin"}},{"$lookup":{"from":"users","localField":"userId","foreignField":"userId","as":"userJoin"}}])