gistfile1.txt

// add the custom static method to the Loopback User model
// note the dollar sign here indicatest to the user this function
// returns an Observable
User.getPointsById$ = function getPointsById$(id) {
  return Observable.create(observer => {
    let isDisposed = false;
    // Here we tap into mongodb method
    // safe ObjectID creation
    // MongoID(id: ObjectID|String) => ObjectID
    // MongoDB requires id's to be of type ObjectID
    const _id = this.app.dataSources.db.connector.getDefaultIdType()(id);
    this.app.dataSources.db.connector
      .collection('user')
      .aggregate([
        { $match: { _id } },
        { $project: { points: { $size: '$progressTimestamps' } } }
      ], (err, [ { points = 1 } = {}]) => {
        if (isDisposed) { return null; }
        if (err) { return observer.onError(err); }
        observer.onNext(points);
        return observer.onCompleted();
      });
    return Disposable.create(() => { isDisposed = true; });
  });