如何轻松地将Observable转换或分配给行为主题,以便其他组件可以共享它

我是Observable样式编程的新手.我有一个问题:我希望在组件之间跨应用程序共享用户信息 - 我使用BehaviorSubject来共享此信息.这是通过将BehaviorSubject共享为AuthInfo来启发的.如果我可以在我的应用程序组件中共享包含uid的AuthInfo,为什么我可以使用它来共享我的用户对象数据？

问题是,用户对象,我是从Firebase获得的.所以它是一个Observable,我不知道如何将它分配给一个行为主题.所以这是我尝试的代码:

  @Injectable()
  export class AuthService {

  static UNKNOWN_USER = new AuthInfo(null);

  static EMPTY_USER = new User(null, null, null, null);

  authInfo$: BehaviorSubject = new BehaviorSubject(AuthService.UNKNOWN_USER);

  userInfo$: BehaviorSubject = new BehaviorSubject(AuthService.EMPTY_USER);

  constructor(private auth: FirebaseAuth, private db:AngularFireDatabase, @Inject(FirebaseRef) fb) {

//firebase way to see if user is login or not
this.auth.subscribe(user => {
  if (user) {
    const authInfo = new AuthInfo(user.uid);
    this.authInfo$.next(authInfo);
    //This is the part I do not know how to do
    [OPTION 1]: this.userInfo$.next(findUserByuid(user.uid)) ?? - error
    [OPTION 2]: this.userInfo$ = findUserByuid(user.uid) ?? - userInfo$ turn into an observerable, which when I logout to call this.userInfo$.next(AuthService.EMPTY_USER) it will  throw error as .next() is not a function.
    [OPTION 3]:
    this.findUserByuid(user.uid).subscribe(user => {
      this.userInfo$.next(user);
    });
    ---- Can I put a subscribe inside of another subscribe to chain it like promise? I am not sure this is following the best practices. But this is the only option that there is no error. But just not sure I am doing it right. I do get the user object no problem

  }
  else {
    this.authInfo$.next(AuthService.UNKNOWN_USER);
  }
});


}

findUserByuid(uid:string):any {
   //return a firebase object observerable
   return this.db.object('userProfile/' + uid).map(user => User.fromJson(user));

}

logout() {

this.userInfo$.next(AuthService.EMPTY_USER);
this.authInfo$.next(AuthService.UNKNOWN_USER);
this.auth.logout();
}

更大的问题是,我应该使用行为主题跨应用程序共享数据吗？或者我应该使用像用户$ = findUserByuid(uid)这样的observable并将user $作为AuthService成员变量.然后其他组件只订阅用户$？

我对在Angular2上共享数据的最佳方法感到困惑,没有使用类似于旧方式Angular 1的虚拟服务.我看到ppl使用Behavior Subject分享auth状态 - 这就是为什么我有所有这些问题和实现.任何帮助将不胜感激!关于行为主题没有太多资源.

[UPDATE]:我选择行为主题的原因而不仅仅是observable在我的应用程序的不同部分之间传递数据: 行为主题VS常规Observable