Angular undefined value outside of subscribe

Issue

I want to use the value from user outside subscribe to assign it to my tweet class. How can i do that because if i try to print it outside subscribe it says undefined..

Here is my code ...

entities

export class Tweet {
    id: number;
    created_at: Date;
    message: string;
    updated_at: Date;
    user: User;

    export class User {
    id?: number;
    username?: string;
    password?: string;
    email?: string;
    imageUrl?: string;
    accountType?: string;
}
}

service

export class UserService {

  private apiServerUrl: string;

  constructor(private http: HttpClient) { 
    this.apiServerUrl = environment.apiBaseUrl;
  }
 public findUserById(userId: number): Observable<User> {
    return this.http.get<User>(`${this.apiServerUrl}/user/${userId}`);
  }

  createTweet(tweet: Tweet) : Observable<Tweet> {
    return this.http.post<Tweet>(`${this.url}/tweet`, tweet);
  }
}

component

 user: User = new User();
    getUser() {
      const id = sessionStorage.getItem('userId');
      this.userService.findUserById(+id).subscribe(response => {
        this.user = response;
        console.log(this.user);
      });

    }


    tweet: Tweet = new Tweet();
    createTweet() {
      this.tweet.message = this.tweetForm.get('text').value;
      this.tweetService.createTweet(this.tweet).subscribe(response => {
        this.tweet = response;
        this.tweet.user = this.user;
      });

    }

Solution

createTweet(): Observable<yourTypeHere> {
  this.tweet.message = this.tweetForm.get('text').value;
  return this.tweetService.createTweet(this.tweet);
}

getUser() {
  const id = sessionStorage.getItem('userId');
  this.userService.findUserById(+id).pipe(
    tap((response) => this.user = response),
    switchMap(() => this.createTweet()) 
  )
  .subscribe((tweetResponse) => {
    this.tweet = response;
    this.tweet.user = this.user;
  });
}

Or using forkJoin:

createTweet(): Observable<yourTypeHere> {
  this.tweet.message = this.tweetForm.get('text').value;
  return this.tweetService.createTweet(this.tweet);
}

getUser(): Observable<anotherTypeHere> {
  this.tweet.message = this.tweetForm.get('text').value;
  return this.tweetService.createTweet(this.tweet);
}

someFunction(): void {
  const myUserAndTweet = forkJoin({
    user: this.getUser(),
    tweet: this.createTweet()  
  });

  myUserAndTweet.subscribe(values => {
     this.user = values.user;
     this.tweet = values.tweet;
     this.tweet.user = this.user;
  });
}

Answered By - Andres2142