mongodb field of array type won't update length when using .push()

Question

Here is the code that is trying to add a user to a schema:

var roomSchema = new Schema({
    name: { type: String, required: true},
    connections: { type: [ { userId: String } ] },
    content: { type: String, default: ""},
    isFull: { type: Boolean, default: false}
});

roomSchema.methods.addUser = function(username, callback) {
this.updateAsync( { $push: { connections: { userId: username }  } } )
.then(function(status) {
    return this.saveAsync();
})
.catch(function(afterPushErr) {
    console.log('After push error');
    throw afterPushErr;
})
.catch(function(saveErr) {
    console.log('save Error');
    throw saveErr;
});

Promise.all(this.connections)
.then(function() {
    if(this.connections.length >= 5) {
        this.updateAsync( { isFull: true })
        .then(function(status) {
            return;
        })
        .catch(function(updateErr) {
            console.log('update Error!');
            throw updateErr;
        });
    }
});

}

and then the code that calls it (which correctly imports the above function): (Note: this is just a quick test function to make sure that there will only be a maximum of 5 users per room)

var populateRooms = function() {
    var names = [
        'asas',
        'asas2',
        'asas3',
        'asas4',
        'asas5',
        'asas6'];

    var emails = [
        'asas@as.ca',
        'asas2@as.ca',
        'asas3@as.ca',
        'asas4@as.ca',
        'asas5@as.ca',
        'asas6@as.ca'];

    for(var i=0; i<6; ++i) {
    Room.findOneAsync( { isFull: false })
        .then(function(freeRoom) {
            var newUser = new User({
                username : names[i],
                email : emails[i],
                password : 'Asasas1',
                isPlaced: true,
                roomName: freeRoom.name
            });
            freeRoom.addUser(newUser.username);
            return newUser;
        })
        .then(function(newUser) {
            newUser.saveAsync();
        })
        .catch(function(err) {
            throw err;
        });
    }
    return true;
}

typically what I will see in the console is just the last user that was pushed rather than the entire list and because of that I am unable to see whether or not the list is of length >= 5.

On the mongo console I see this for the room schema:

{ "_id" : ObjectId("5882c3eefab3081700444972"), "name" : "1484964846968_0", "isFull" : false, "content" : "", "connections" : [ { "userId" : "asas5", "_id" : ObjectId("5882c3effab308170044497f") }, { "userId" : "asas6", "_id" : ObjectId("5882c3effab308170044497d") }, { "userId" : "asas4", "_id" : ObjectId("5882c3effab3081700444981") }, { "userId" : "asas6", "_id" : ObjectId("5882c3effab308170044497d") }, { "userId" : "asas5", "_id" : ObjectId("5882c3effab308170044497f") }, { "userId" : "asas4", "_id" : ObjectId("5882c3effab3081700444981") }, { "userId" : "asas3", "_id" : ObjectId("5882c3effab3081700444983") }, { "userId" : "asas", "_id" : ObjectId("5882c3effab3081700444987") }, { "userId" : "asas2", "_id" : ObjectId("5882c3effab3081700444985") }, { "userId" : "asas3", "_id" : ObjectId("5882c3effab3081700444983") }, { "userId" : "asas2", "_id" : ObjectId("5882c3effab3081700444985") }, { "userId" : "asas", "_id" : ObjectId("5882c3effab3081700444987") } ], "__v" : 12 } { "_id" : ObjectId("5882c3eefab3081700444973"), "name" : "1484964846978_1", "isFull" : false, "content" : "", "connections" : [ ], "__v" : 0 } { "_id" : ObjectId("5882c3eefab3081700444974"), "name" : "1484964846980_2", "isFull" : false, "content" : "", "connections" : [ ], "__v" : 0 } { "_id" : ObjectId("5882c3eefab3081700444975"), "name" : "1484964846980_3", "isFull" : false, "content" : "", "connections" : [ ], "__v" : 0 } { "_id" : ObjectId("5882c3eefab3081700444976"), "name" : "1484964846981_4", "isFull" : false, "content" : "", "connections" : [ ], "__v" : 0 } { "_id" : ObjectId("5882c3eefab3081700444977"), "name" : "1484964846981_5", "isFull" : false, "content" : "", "connections" : [ ], "__v" : 0 } { "_id" : ObjectId("5882c3eefab3081700444978"), "name" : "1484964846982_6", "isFull" : false, "content" : "", "connections" : [ ], "__v" : 0 } { "_id" : ObjectId("5882c3eefab3081700444979"), "name" : "1484964846984_7", "isFull" : false, "content" : "", "connections" : [ ], "__v" : 0 } { "_id" : ObjectId("5882c3eefab308170044497a"), "name" : "1484964846984_8", "isFull" : false, "content" : "", "connections" : [ ], "__v" : 0 } { "_id" : ObjectId("5882c3eefab308170044497b"), "name" : "1484964846984_9", "isFull" : false, "content" : "", "connections" : [ ], "__v" : 0 }

Edit this is the new error on the promise code for addUser

(node:4648) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): TypeError: Cannot read property 'connections' of undefined (node:4648) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): TypeError: Cannot read property 'connections' of undefined After push error After push error save Error save Error Unhandled rejection TypeError: Cannot read property 'saveAsync' of undefined at C:\someApp\app\models\room-model.js:19:14 at tryCatcher (C:\someApp\node_modules\bluebird\js\release\util.js:16:23)

score 1 · Answer 1 · edited May 23 '17 at 12:08

1

In the test function, you put the asynchronous call(Room.findOne) inside the for loop. Thus you got the same freeZoom for each loop.(which is not what you want)

Check this question: Asynchronous Process inside a javascript for loop

Another suggestion, this.update inside the addUser function is also asynchronous and may not act like what you want in some situation.

edited May 23 '17 at 12:08

Community

1
1

answered Jan 21 '17 at 10:41

hankchiutw

1,546
1
12
15

So the point is that the first 5 queries will return the same one; and after they find a room a user is added and both the room and the user is saved. – Emil Kais Jan 21 '17 at 17:30
the first room at the end has 6 users, meaning that the only thing missing is a stopping point for the push when the room is full (there are 5 people in there). – Emil Kais Jan 21 '17 at 17:34
maybe you could use mongoose query as [promises](http://mongoosejs.com/docs/promises.html), instead of callback style. – hankchiutw Jan 22 '17 at 06:43
So I was able to get the script to add a user Asynchronously (presumably so I will edit the above code to reflect that. However it looks like the core of the error is the addUser function and making sure that everything happens in order. I will also show the new code to reflect those changes, I am getting a new error: cannot save property of undefined. – Emil Kais Jan 24 '17 at 01:00

mongodb field of array type won't update length when using .push()

1 Answers1