Managing my own custom Id's

[Jean-Bernard Moens]

Hi,

I'd like to manage my own Id's (as the default ones are pretty long and consume bandwidth). The difficulty is that I need to create them (say, by incrementing a counter). But I need to do this in a concurrent environment (Node.JS). Is there a simple example I could follow that creates a schema, with a custom _id and a method(?) that automatically generates the next unique _id, whenever a new document is created?

Thanks,

JB

[Mongo Rookie]

Look here:
http://docs.mongodb.org/manual/tutorial/create-an-auto-incrementing-field/

Translated to mongoose:

module.exports = function(mongoose) {
  // Creates a new Mongoose Schema object
  var Schema = mongoose.Schema;  

  // Collection to hold counters/sequences for ids
  var CountersSchema = new Schema({  
      _id: { type: String, required: true },  
      sequence: { type: Number, required: true }
    },{
      versionKey: false
    }
  );

  // Creates the Model for the Attachments Schema
  var Counters = mongoose.model('Counters', CountersSchema);

  var getNext = function(collection, callback) {
    var query = {_id: collection};
    var update = {$inc: {sequence: 1}};
    var options = {upsert: true};
    Counters.findOneAndUpdate(query, update, options, function(err, counter) {
      if (err) // handle error

      callback(counter.sequence);
    });
  }


  return {
    getNext: getNext
  }
}

Now you can do something like:

getNext('person', function(id) {
  // create a new person with the next id
});

This allows you to have a counter/sequence for multiple 'collections', ie I would use this for my person collection.

Please be aware of this.  Probably more more of an issue than consuming bandwidth for a few extra characters in an id.

Warning

Generally in MongoDB, you would not use an auto-increment pattern for the _id field, or any field, because it does not scale for databases with larger numbers of documents. Typically the default value ObjectId is more ideal for the _id.