valueChanges does not inherit type of list/object

[Maistho]

Version info

Angular: 4.4.4

Firebase: 4.5.0

AngularFire: 5.0.0-rc.0-next

The problem

AngularFireList and AngularFireObject has a generic T that is not inherited to all of it's members, such as valueChanges or snapshotChanges.

Is it possible to have a generic for snapshotChanges? It returns a SnapshotAction, which in turn contains a firebase.database.DataSnapshot, which is not generic.

Links to related Interfaces
AngularFireList
AngularFireObject

The fix

(if I'm correct)

--- a/src/database/interfaces.ts
+++ b/src/database/interfaces.ts
@@ -5,7 +5,7 @@ export type FirebaseOperation = string | firebase.database.Reference | firebase.
 
 export interface AngularFireList<T> {
   query: DatabaseQuery;
-  valueChanges<T>(events?: ChildEvent[]): Observable<T[]>;
+  valueChanges(events?: ChildEvent[]): Observable<T[]>;
   snapshotChanges(events?: ChildEvent[]): Observable<SnapshotAction[]>;
   stateChanges(events?: ChildEvent[]): Observable<SnapshotAction>;
   auditTrail(events?: ChildEvent[]): Observable<SnapshotAction[]>;
@@ -17,8 +17,8 @@ export interface AngularFireList<T> {
 
 export interface AngularFireObject<T> {
   query: DatabaseQuery;
-  valueChanges<T>(): Observable<T | null>;
-  snapshotChanges<T>(): Observable<SnapshotAction>;
+  valueChanges(): Observable<T | null>;
+  snapshotChanges(): Observable<SnapshotAction>;
   update(data: T): Promise<any>;
   set(data: T): Promise<void>;
   remove(): Promise<any>;

Should I open a PR?

[Toxicable]

valueChanges does return an Observable<T[]>
https://github.com/angular/angularfire2/blob/master/src/database/interfaces.ts#L8

[Maistho]

@Toxicable

Yup, but I need to specify the generic twice:

this.db.list<MyInterface>('/stuff')
  .valueChanges<MyInterface>();

Whereas this is much more preferable:

this.db.list<MyInterface>('/stuff')
  .valueChanges(); // currently returns Observable<{}[]>

[Maistho]

Also this is "valid" code currently:

let stuff = this.db.list<number>('/stuff'); // stuff is a list of numbers, sure

let stuff$ = stuff.valueChanges<string>(); // wait, it's a list of strings now?

stuff.push(1); // But I can push a number?

[Toxicable]

Yup, but I need to specify the generic twice:

No you don't see here, https://stackblitz.com/edit/angular-template-firebase-uxldsj?file=app%2Fapp.module.ts
var items is typed to Observable<Item[]>

if you second example you're overriding the generic with another, which is fine.
stuff$ will be typed as a generic of stringbutstuffis still typed as a generic ofnumber`, I don't see an issue here

[Maistho]

@Toxicable Your example is for Cloud Firestore, not Realtime Database.

If I modify your example to use the Realtime Database, it fails.

https://stackblitz.com/edit/angular-template-firebase-7mn3ay

[Maistho]

Also, Firestore does not have a generic specific for collection.valueChanges, but rather uses the one already on the collection.

https://github.com/angular/angularfire2/blob/master/src/firestore/collection/collection.ts#L98