mongoose-id-autoinc/lib/mongoose-id-autoinc.js

Creating of auto increment id fields

/**
 * @author MarioDu <dujiakun@gmail.com>
 */

module.exports = new (function () {

  var db, Counter, mongoose, counterName;

  this.plugin = function(schema, options) {

    if (!options.model)
      throw new Error('Missing required parameter: model');

    options.model = options.model.toLowerCase() + 'unikey';
    options.field = options.field || 'unikey';
    //don't use _id, keep it
    options.start = (!isNaN(options.start)) ? options.start : 1;
    options.step = (!isNaN(options.step)) ? options.step : 1;

    var fields = {},
        ready  = false;

    // Adding new field into schema
    fields[options.field] = {
      type:    Number,
      unique:  true,
      require: true
    };
    schema.add(fields);

    // Initializing of plugin
    Counter.findOne({
      model: options.model,
      field: options.field
    }, function (err, res) {
      if (!res)
        (new Counter({
          model: options.model,
          field: options.field,
          seq:   options.start
        })).save(function () {
          ready = true;
        });
      else
        ready = true;
    });

    schema.pre('save', function (next) {

      var doc = this;

      // Increment method refer to http://docs.mongodb.org/manual/tutorial/create-an-auto-incrementing-field/,
      // first method
      function save () {

        if (ready)
          Counter.collection.findAndModify({
            model: options.model,
            field: options.field
          }, [], {
            $inc: {
              seq: options.step
            }
          }, {
            'new':  true,
            upsert: true
          }, function (err, res) {

            if (!err)
              doc[options.field] = res.seq - options.step;
            next(err);
          });
        else
          setTimeout(save, 5);
          // Delay before plugin will be sucessfully initialized
      }
      save();
    });
  };

  this.init = function (database, counter) {

    db          = database;
    mongoose    = require('mongoose');
    counterName = counter || 'counter';

    var schema = new mongoose.Schema({
      model: {
        type:    String,
        require: true
      },
      field: {
        type:    String,
        require: true
      },
      seq: {
        type:     Number,
        default:  1
      }
    });
    schema.index({ field: 1, model: 1 }, { unique: true, required: true, index: -1 });

    Counter = db.model(counterName, schema);
  };

})();