如何在Node.js中添加promise.all在循环中顺序化findOrCreate？

Question

I create two models in sequelize. I got array of results "Users" and than loop through to get or create new "Room" based on User.id. I want to print all rooms after all is done. I got empty array in console, because its asynchronious. How can I call console.log after creating all Rooms?

var Users = sequelize.import(__dirname + "/../models/own/user");
var Rooms = sequelize.import(__dirname + "/../models/own/room");    
var _this = this;

this.users = [];
this.rooms = [];

Users.findAll().then(function(users) {
    _this.users = users;

    users.forEach(function(user){

        Rooms.findOrCreate({where: {user_id: user.get('id')}})
        .spread(function(room, created) {
          _this.rooms.push(
            room.get({
              plain: true
            })
          );

        });

    });

    console.log(_this.rooms)

});

Answer 1

You can execute array of promises through Promise.all:

var promises = users.map(function(user){
    return Rooms.findOrCreate({where: {user_id: user.get('id')}});
});
Promise.all(promises).then(function(dbRooms){
    for(var key in dbRooms){
        _this.rooms.push(dbRooms[key][0].get({plain: true}));
    }
    console.log(_this.rooms);
});

Answer 2

Try putting console.log in .then function. Chain it after .spread. I believe an array of the rooms will be passed as an argument to the first callback:

.then(function(rooms){
    ...
})

or,

you may try to refactor your code and put your logic in a .then function.

Rooms.findOrCreate({where: {user_id: user.get('id')}})
.then(function(rooms, created) {
    var room;

    for(var i in rooms){
        room = rooms[i];

        _this.rooms.push(
            room.get({
                plain: true
            })
        );
    }
});