CODEWITHSUNDEEP
javascriptmongodbmongoose
Varun Narayanan
Varun Narayanan

Reputation: 343

Mongoose child objects added to parent object not saved correctly

I have a Schema called Players and another one called Game. Every Games has an attribute called players which is an array of references to player objects.

Game Schema

let GameSchema = new mongoose.Schema({
    players: [{
        ref: "Player",
        type: mongoose.Schema.Types.ObjectId,
    }],
    created: {
        type: Date,
        default: Date.now,
    }
}, { usePushEach: true });

PlayerSchema

let PlayerSchema = new mongoose.Schema({
    parentGameId: mongoose.Schema.Types.ObjectId,
    idInGame: Number,
    points: Number,
});

MongoDb Connection

mongoose.Promise = global.Promise;
mongoose.connect("mongodb://localhost/ScoreKeeper", { useMongoClient: true });

Code for initializing Games and Players on the post route. (I am using Express)

app.post('/', function(req, res) {
    let players = Number(req.body.players);
    Game.create({
        players: [],
    }, function(error, newGame) {
        if (error) {
            console.log(error);
        } else {
            let currentGameID = newGame._id;
            for (let i = 1; i <= players; i++) {
                Player.create({
                    parentGameId: currentGameID,
                    idInGame: i,
                    points: 0
                }, function(error, newPlayer) {
                    if (error) {
                        console.log(error);
                    } else {  
                        newGame.players.push(newPlayer._id);
                        newGame.save(function(error, newGame) {
                            if (error) {
                                console.log(error);
                            } else {
                                console.log("New Player added");
                            }
                        });

                    }
                });
            }
        }

    });
});

On Terminal on the node console I have the following output, when I create 5 players:

New Player added

New Player added

New Player added

New Player added

New Player added

Now when I go to the mongo console and check out the players collection, I find there are 5 players created as expected. Using "db.players.find()"

{ "_id" : ObjectId("5a6159685d3dabb00d0065b0"), "parentGameId" : ObjectId("5a6159685d3dabb00d0065af"), "idInGame" : 1, "points" : 0, "__v" : 0 }

{ "_id" : ObjectId("5a6159685d3dabb00d0065b1"), "parentGameId" : ObjectId("5a6159685d3dabb00d0065af"), "idInGame" : 2, "points" : 0, "__v" : 0 }

{ "_id" : ObjectId("5a6159685d3dabb00d0065b2"), "parentGameId" : ObjectId("5a6159685d3dabb00d0065af"), "idInGame" : 3, "points" : 0, "__v" : 0 }

{ "_id" : ObjectId("5a6159685d3dabb00d0065b3"), "parentGameId" : ObjectId("5a6159685d3dabb00d0065af"), "idInGame" : 4, "points" : 0, "__v" : 0 }

{ "_id" : ObjectId("5a6159685d3dabb00d0065b4"), "parentGameId" : ObjectId("5a6159685d3dabb00d0065af"), "idInGame" : 5, "points" : 0, "__v" : 0 }

However when I check the game object in the mongo console, I find this ...

db.games.findOne()

{

"_id" : ObjectId("5a6159685d3dabb00d0065af"),

"created" : ISODate("2018-01-19T02:35:20.632Z"),

"players" : [

    ObjectId("5a6159685d3dabb00d0065b1"),

    ObjectId("5a6159685d3dabb00d0065b1"),

    ObjectId("5a6159685d3dabb00d0065b0"),

    ObjectId("5a6159685d3dabb00d0065b1"),

    ObjectId("5a6159685d3dabb00d0065b0"),

    ObjectId("5a6159685d3dabb00d0065b2"),

    ObjectId("5a6159685d3dabb00d0065b3"),

    ObjectId("5a6159685d3dabb00d0065b3"),

    ObjectId("5a6159685d3dabb00d0065b4")

],

"__v" : 5

}

There is a mismatch between Games and Players, I feel that the bug is in saving the newGame after adding newPlayer. Strangely enough _v property reads 5 as expected. Could you please point me towards fixing the bug?

Thank-you

Upvotes: 0

Views: 1373

Answers (1)

Saravana
Saravana

Reputation: 12817

There is a bug in saving the game document in your code

Instead of save use update method with push to add ObjectIds of players

newGame.update({$push:{players : newPlayer._id} }, function(error, newGame) {...}

console out

Mongoose: games.insert({ _id: ObjectId("5a6168c12478110e7aa74d5d"), created: new Date("Fri, 19 Jan 2018 03:40:49 GMT"), players: [], __v: 0 })
Mongoose: players.insert({ parentGameId: ObjectId("5a6168c12478110e7aa74d5d"), idInGame: 1, points: 0, _id: ObjectId("5a6168c12478110e7aa74d5e"), __v: 0 })
Mongoose: players.insert({ parentGameId: ObjectId("5a6168c12478110e7aa74d5d"), idInGame: 2, points: 0, _id: ObjectId("5a6168c12478110e7aa74d5f"), __v: 0 })
Mongoose: players.insert({ parentGameId: ObjectId("5a6168c12478110e7aa74d5d"), idInGame: 3, points: 0, _id: ObjectId("5a6168c12478110e7aa74d60"), __v: 0 })
Mongoose: players.insert({ parentGameId: ObjectId("5a6168c12478110e7aa74d5d"), idInGame: 4, points: 0, _id: ObjectId("5a6168c12478110e7aa74d61"), __v: 0 })
Mongoose: players.insert({ parentGameId: ObjectId("5a6168c12478110e7aa74d5d"), idInGame: 5, points: 0, _id: ObjectId("5a6168c12478110e7aa74d62"), __v: 0 })
Mongoose: games.update({ _id: ObjectId("5a6168c12478110e7aa74d5d") }, { '$push': { players: ObjectId("5a6168c12478110e7aa74d62") } }, {})
Mongoose: games.update({ _id: ObjectId("5a6168c12478110e7aa74d5d") }, { '$push': { players: ObjectId("5a6168c12478110e7aa74d5f") } }, {})
Mongoose: games.update({ _id: ObjectId("5a6168c12478110e7aa74d5d") }, { '$push': { players: ObjectId("5a6168c12478110e7aa74d61") } }, {})
Mongoose: games.update({ _id: ObjectId("5a6168c12478110e7aa74d5d") }, { '$push': { players: ObjectId("5a6168c12478110e7aa74d60") } }, {})
Mongoose: games.update({ _id: ObjectId("5a6168c12478110e7aa74d5d") }, { '$push': { players: ObjectId("5a6168c12478110e7aa74d5e") } }, {})

mongo CLI

> db.players.find()
{ "_id" : ObjectId("5a6168c12478110e7aa74d5f"), "parentGameId" : ObjectId("5a6168c12478110e7aa74d5d"), "idInGame" : 2, "points" : 0, "__v" : 0 }
{ "_id" : ObjectId("5a6168c12478110e7aa74d61"), "parentGameId" : ObjectId("5a6168c12478110e7aa74d5d"), "idInGame" : 4, "points" : 0, "__v" : 0 }
{ "_id" : ObjectId("5a6168c12478110e7aa74d5e"), "parentGameId" : ObjectId("5a6168c12478110e7aa74d5d"), "idInGame" : 1, "points" : 0, "__v" : 0 }
{ "_id" : ObjectId("5a6168c12478110e7aa74d60"), "parentGameId" : ObjectId("5a6168c12478110e7aa74d5d"), "idInGame" : 3, "points" : 0, "__v" : 0 }
{ "_id" : ObjectId("5a6168c12478110e7aa74d62"), "parentGameId" : ObjectId("5a6168c12478110e7aa74d5d"), "idInGame" : 5, "points" : 0, "__v" : 0 }
> 
> 
> db.games.find().pretty()
{
    "_id" : ObjectId("5a6168c12478110e7aa74d5d"),
    "created" : ISODate("2018-01-19T03:40:49.028Z"),
    "players" : [
        ObjectId("5a6168c12478110e7aa74d62"),
        ObjectId("5a6168c12478110e7aa74d5f"),
        ObjectId("5a6168c12478110e7aa74d61"),
        ObjectId("5a6168c12478110e7aa74d60"),
        ObjectId("5a6168c12478110e7aa74d5e")
    ],
    "__v" : 0
}
>

Upvotes: 1

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