javascript - Angular 2 Firebase storage url in FirebaseObjectObservable -

i trying create object contains url storage. have been trying use rxjs merge these 2 observables one, far has not worked out.

this.database.object(`objects/1`); 

when subscribe follow object in it:

{     name: '-' } 

but want/need this:

{     name: '-',     image_url: '[storage_url]' } 

so use storage reference merge them, not able find examples done.

this.storage()     .child(`objects/1/image.png`)     .getdownloadurl()     .then((url) => url, () => '') 

how can merge storage url firebaseobjectobservable?