Question

我有2个兄弟组件，我想访问另一个组件中要访问的一个组件的一个变量。我使用共享服务，但它不起作用。你能告诉我哪里错了吗？

服务：

@Injectable()
export class SharedService{
  private isSuccess = new Subject<boolean>();
  getSaveBtnStatus(){
    return this.isSuccess.asObservable();
  }
  setSaveBtnStatus(value: boolean){
    this.isSuccess.next(value);
  }
}

组件1：

@Injectable()
export class LoginComponent implements OnInit {
  constructor(private http: Http, private route: ActivatedRoute, private router: Router, private myshared: SharedService) {
  }

  ngOnInit() {    
  }

  login = (user) => {
    var username = user.username;
    var password = user.password;
    var user_api , user_birth ;
    var url = 'https://swapi.co/api/people/?search='+username;
    this.http.get(url).subscribe(data => { 
      var count = data.json().count;
      if( count == 0 )alert("NO such user");
    if( count > 0 ) {
      user_api= (data.json().results[0].name);
      user_birth = (data).json().results[0].birth_year;
      if( password == user_birth && username == user_api ) {
        console.log("Successful");
        this.myshared.setSaveBtnStatus(true);// using shared service
        this.router.navigate(['/search']);
     } else if ( password != user_birth || username != user_api) 
       alert("CHECK Your Username and Passowrd");
   }
  })
  }
}

组件2：

export class SearchPlanetComponent implements OnInit {
  form;
  private loading: boolean = false;
  private results: Observable<Array<String>>;
  public searchField : FormControl
  private isSuccess :Boolean
  constructor(private myservice: SearchService,
    private myshared:SharedService, private http: Http) {
  }
  ngOnInit() {
    this.myshared.getSaveBtnStatus().
      subscribe(
        data => console.log(data) // nothing is printed in console.
      );
}

请说明为什么服务功能获取/设置不起作用？

Answer 1

它不起作用，因为当你在主题内发出值时，底层组件被认为是没有加载的。调用router.navigate后，该组件将被加载。

您应该考虑使用BehaviorSubject代替Subject，因为BehaviourSubject会保留最后一次发布的值。当有人订阅它时，它也会发出last/inital持久值。

//it needs initial state while registering it, so passed false
private isSuccess = new BehaviorSubject<boolean>(false);

角度为4的两个兄弟组件之间的可变共享？

1 个答案: