How to sort array of embedded documents via Mongoose query?

Question

I'm building a node.js application with Mongoose and have a problem related to sorting embedded documents. Here's the schema I use:

var locationSchema = new Schema({
    lat: { type: String, required: true },
    lon: { type: String, required: true },
    time: { type: Date, required: true },
    acc: { type: String }
})

var locationsSchema = new Schema({
    userId: { type: ObjectId },
    source: { type: ObjectId, required: true },
    locations: [ locationSchema ]
});

I'd like to output the locations embedded in the userLocations documented sorted by their time attribute. I currently do the sorting in JavaScript after I retrieved the data from MongoDb like so:

function locationsDescendingTimeOrder(loc1, loc2) {
   return loc2.time.getTime() - loc1.time.getTime()
}

LocationsModel.findOne({ userId: theUserId }, function(err, userLocations) { 
   userLocations.locations.sort(locationsDescendingTimeOrder).forEach(function(location) {
      console.log('location: ' + location.time);
   }
});

I did read about the sorting API provided by Mongoose but I couldn't figure out if it can be used for sorting arrays of embedded documents and if yes, if it is a sensible approach and how to apply it to this problem. Can anyone help me out here, please?

Thanks in advance and cheers, Georg

score 4 · Accepted Answer · answered Feb 21 '12 at 03:11

4

You're doing it the right way, Georg. Your other options are either to sort locations by time upon embedding in the first place, or going the more traditional non-embedded route (or minimally embedded route so that you may be embedding an array of ids or something but you're actually querying the locations separately).

answered Feb 21 '12 at 03:11

glortho

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Thanks Jed. I ended up using the approach you proposed - sorting the locations upon embedding. Works fine for me. – BumbleGee Feb 23 '12 at 16:36
That's my problem too, but how can I sort embedded documents upon embedding ? – drinchev Apr 01 '12 at 13:10
I've figured it out. You probably mean when adding new document via .push OR .unshift it will be positioned correctly. – drinchev Apr 01 '12 at 13:34

score 0 · Answer 2 · answered Dec 01 '20 at 12:13

This also can be done using mongoose sort API as well.

LocationsModel.findOne({ userId: theUserId })
//    .sort({ "locations.time": "desc" }) // option 1
    .sort("-locations.time")              // option 2
    .exec((err, result) => {
        // compute fetched data
    })

Sort by field in nested array with Mongoose.js

More methods are mentioned in this answer as well

Sorting Options in mogoose

Mongoose Sort API

How to sort array of embedded documents via Mongoose query?

2 Answers2

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