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

Answer 1

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).