I am trying to return returned properties, much like in Mysql's AS. But with renamed object properties.

Query

Games.find({leagueID:leagueID, result:{$ne: null}}).populate('home_id away_id').sort({date: -1}).execAsync()

Output

{
    home_id: {
        ...some details
    },
    away_id: {
        ...some details
    }
}

Desired Output

{
    home: {
        ...some details
    },
    away: {
        ...some details
    }
}

So how can I get the desired oute?

I am trying to return returned properties, much like in Mysql's AS. But with renamed object properties.

Query

Games.find({leagueID:leagueID, result:{$ne: null}}).populate('home_id away_id').sort({date: -1}).execAsync()

Output

{
    home_id: {
        ...some details
    },
    away_id: {
        ...some details
    }
}

Desired Output

{
    home: {
        ...some details
    },
    away: {
        ...some details
    }
}

So how can I get the desired oute?

• javascript
• node.js
• mongodb

• How about just caliing them "home" and "away" to begin with since your only intent seems to be to populate that with the related object. Otherwise you basically need to convert the mongoose documents returned to standard objects, create new keys, copy data, then remove old keys. Seems that just naminng them what you want is the most logical thing to do for your end result. – Blakes Seven Commented Sep 25, 2015 at 7:48

3 Answers 3

My solution is to use the transform function.

GamesSchema.set('toJSON', {
    transform: function(doc, ret, options) {   
        if (mongoose.Types.ObjectId.isValid(ret.home)) {
            ret.homeId = ret.home;
            delete ret.home;
        }
        if (mongoose.Types.ObjectId.isValid(ret.away)) {
            ret.awayId = ret.away;
            delete ret.away;
        }
    }
});

Without populate:

Input

{
    "_id": "sD95OhsGrWVIqmTLVeuQdkna",
    "leagueID": 1000,
    "home": "404d1d9f68c3bb386b50f440" // ObjectId
    "away": "504d1d9f68c3bb386b50f450" // ObjectId
}

Output

{
    "_id": "sD95OhsGrWVIqmTLVeuQdkna",
    "leagueID": 1000,
    "homeId": "404d1d9f68c3bb386b50f440"
    "awayId": "504d1d9f68c3bb386b50f450"
}

With populate:

Input

{
    "_id": "sD95OhsGrWVIqmTLVeuQdkna",
    "leagueID": 1000,
    "home": "404d1d9f68c3bb386b50f440" // ObjectId
    "away": "504d1d9f68c3bb386b50f450" // ObjectId
}

Output

{
    "_id": "sD95OhsGrWVIqmTLVeuQdkna",
    "leagueID": 1000,
    "home": {
        "_id": "404d1d9f68c3bb386b50f440",
        "name": "Home"
    }
    "away": {
        "_id": "504d1d9f68c3bb386b50f450",
        "name": "Away"
    }
}

You can use aggregation and manipulate the output field like this

db.collection.aggregate([{ $project:{_id:0, home:"$home_id", away:"$away_id"} }])

Try lodash's _.mapKeys, like this:

const newObject = _.mapKeys(oldObject.toJSON(), (value, key) => {
            if (key === 'oldKey') return 'newKey';
            return key;
          });