Getting error assignable to parameter of type

Question

I am using "rxjs": "~6.2.0" in below code block

    canActivate():Observable<boolean>
     {
      return this.auth.user$.pipe
      (
        switchMap( 
                 user => 
                   {
                   return this.userService.get(user.uid);
                   }
                 )
       ).pipe( map( appUser => appUser.isAdmin))
     }

The get method of userService has below logic.

    get(uid : string): AngularFireObject<AppUser>
      {
        return this.db.object('/users/'+ uid);
      }

I am getting error

"Argument of type '(user: User) => AngularFireObject' is not assignable to parameter of type '(value: User, index: number) => ObservableInput'. Type 'AngularFireObject' is not assignable to type 'ObservableInput'. Type 'AngularFireObject' is not assignable to type 'Iterable'. Property '[Symbol.iterator]' is missing in type 'AngularFireObject'."

Answer 1

You need not use two pipes here, map the result appUser.isAdmin using the same pipe.

canActivate():Observable<boolean>
{
      return this.auth.user$
       .pipe(
           switchMap(user => this.userService.get(user.uid)), 
           map(appUser => appUser.isAdmin)
       )
}

Also you should modify userService.get() to return proper Observable which you get from valueChanges()

get(uid : string): Observable<any>
{
     return this.db.object('/users/'+ uid).valueChanges();
}

Answer 2

The argument passed to SwitchMap should be an Observable, but this.userService.get(user.uid) returns a AngularFireObject<AppUser>.

AngularFireObject is from AngularFire. I haven't used AngularFire, but from what I get you have to call valueChanges() on the AngularFireObject in order to get an Observer. So if you can change the UserService, it should look like this:

get(uid : string): Observable<AppUser>
{
    return this.db.object('/users/'+ uid).valueChanges();
}

And as Amit Chigadani mentioned, you should put the switchMap and map in the same pipe, as well as simplifying the arrow function in the switchMap.