CODEWITHSUNDEEP
typescriptrxjsobservablerxjs6
Beto Neto
Beto Neto

Reputation: 4102

Neasted RXJS Observables

I'm using RXJS 6.5.4

In my typescript service I have:

isAuthenticated(): Observable<boolean> {
   // request
}
currentUserPromise(): Promise<User> {
   // request the User model and return via Promise.
}

My second method, I need to verify if the session is authenticated, then request the current user and transform this to another Observable to resolve if the current user is an admin.

I'm trying this, but I'm getting errors:

isAdmin(): Observable<boolean> {   
   this.isAuthenticated().pipe(map(authenticated => {
      if (authenticated) {   
          return from(this.currentUserPromise().then(user => user.roles.indexOf('ADMIN') > -1)
      }
      return mapTo(false); // there is no authentication, so no current user and no admin!
   }));
}

And this is the compile error:

Type 'Observable<Observable<boolean>>' is not assignable to type 'Observable<boolean>'.
   Type 'Observable<boolean>' is not assignable to type 'boolean'.ts(2322)

Upvotes: 1

Views: 46

Answers (1)

bryan60
bryan60

Reputation: 29325

if you need to subscribe to an inner observable, you need a higher order operator like switchMap, map is for synchronous data transforms. mapTo is an operator and can't be used like you were using it, use of to turn a value into an observable... also you need to return it for it to be subscribed to.

isAdmin(): Observable<boolean> {   
   return this.isAuthenticated().pipe(switchMap(authenticated => {
      if (authenticated) {   
          return from(this.currentUserPromise().then(user => user.roles.indexOf('ADMIN') > -1))
      }
      return of(false); // there is no authentication, so no current user and no admin!
   }));
}

Upvotes: 2

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