Cast Query Observable to FirebaseListObservable

[davideast]

If you create a query on a FirebaseListObservable the methods such as .push(), .remove(), and .update() are never attached.

// a non-queried list
cost regularList = af.database.list(`/items`);

// a queried list
const queriedList = af.database.list(`/items`, {
  query: { limitToLast: 25 }
});

// works
regularList.push({ name 'item' });

// won't work
queriedList.push({ name: 'item' });

I believe this is because a query creates a regular Observable, and then a mergeMap is used to create a FirebaseListObservable.

Any ideas on how to solve this issue, @Blesh?

[benlesh]

@davideast you'd need to create a custom Observable that overrides lift to return it's own type.
Something like:

class FirebaseListObservable<T> extends Observable<T> {
   /* stuff here */
  lift<R>(operator: Operator<T, R>): FirebaseListObservable<R> {
    const observable = new FirebaseListObservable<R>();
    observable.source = this;
    observable.operator = operator;
    return observable;
  }
}

This is because lift is used in every operator to create the operation/effect. Take map for example

[benlesh]

Another thing to do is question whether or not is that you want a custom Observable type, or you want a class that has an observable as a property on it. It really depends on the ergonomics you're aiming for.

[ian-a-hickey]

Is there a work around for this issue?

[ian-a-hickey]

Thanks for the update @davideast.