Question

我正在使用带有Typescript的Angular2。假设我有一个虚拟登录组件和一个认证服务来进行令牌认证。一旦从后端服务器获取令牌，我将在authenticated函数中设置map变量。

问题是我无法访问链接函数中的实例变量。链接函数内的this实际上是此可观察对象的订阅者。我知道这是一个范围问题，但无法弄明白。

export class AuthenticationService {
authenticated:boolean = false; //this is the variable I want to access

constructor(public http: Http) {
    this.authenticated = !!sessionStorage.getItem('auth_token');
}

login(username, password) {
    let headers = new Headers();
    headers.append('Content-Type', 'application/json');

    return this.http
      .post(
        'http://localhost:8080/token-auth',
        JSON.stringify({ username, password }),
        { headers }
      )
      .map(res => res.json())
      .map((res) => { 
        if (res) {
            this.authenticated = true;  //this is where I want to access the instance variable
            sessionStorage.setItem('auth_token', res.token);
        }

        return res;
      });
}

调用上述login()方法的dummy-login组件是这样的：

export class DummyLoginComponent {
  constructor(private auth: AuthenticationService, private router: Router) {
  }

  onSubmit(username, password) {

    this.auth.login(username, password).subscribe((result) => {
        if (result) {
            this.router.navigate(['Dashboard']);
        }
    })
  }
}

Answer 1

您可以订阅observable而不是映射

login(username, password) {
    let headers = new Headers();
    headers.append('Content-Type', 'application/json');

    let res = this.http
      .post(
        'http://localhost:8080/token-auth',
        JSON.stringify({ username, password }),
        { headers }
      )
      .map(res => res.json());
    res.subscribe(
      (res) => { 
            this.authenticated = true;  //this is where I want to access the instance variable
            sessionStorage.setItem('auth_token', res.token);
    });
    return res;
}

Angular2 / Typescript：从链接可观察函数中访问实例变量

1 个答案: