错误后可观察到 rx 损坏

Question

我正在尝试使用 ngrx store + ng effects 为我的应用程序编写登录流程。我设法编写了它并且它在快乐的场景中工作，但是当用户向表单输入错误的值时，服务器以 401 响应，下一次登录尝试无效。我已经读到在使用可观察对象时必须捕获异常以避免 'break' 流，但据我所知我捕获了异常并且它现在仍在工作。

代码下方；

export class LoginComponent {

  logged = new Observable<any>();

  constructor(private store: Store<AppStore>) {
   this.logged = store.select('login');
  }

  login(username: string, password: string){
    let body = JSON.stringify({username, password});
    this.store.dispatch({type: LoginActions.ATTEMPT_LOGIN, payload: body});
  }

}

@Injectable()
export class LoginEffects {

  constructor(
    private actions: Actions,
    private loginService: LoginService
  ) { }

  @Effect() login = this.actions
    .ofType(LoginActions.ATTEMPT_LOGIN)
    .map(toPayload)
    .switchMap(payload => this.loginService.attemptLogin(payload))
    .map(response => new LoginActions.LoginSuccess(response))
    .catch(error => of(new LoginActions.LoginFailed(error)));

  @Effect() success = this.actions
    .ofType(LoginActions.LOGIN_SUCCESS)
    .map(toPayload)
    .map(payload => localStorage.setItem(Global.TOKEN, payload))
    .map(() => go(['/menu']));

  @Effect() error = this.actions
    .ofType(LoginActions.LOGIN_FAILED)
    .map(toPayload)
    .map(payload => console.log(payload))
    .ignoreElements();
}

export const login = (state: any = null, action: Actions) => {
  switch (action.type) {
    case LoginActions.ATTEMPT_LOGIN:
      console.log('hello from reducer attempt login');
      return action.payload;
    case LoginActions.LOGIN_SUCCESS:
      console.log('hello from reducer success login');
      return action.payload;
    case LoginActions.LOGIN_FAILED:
      console.log('hello from reducer failed login');
      return action.payload;
    default:
      return state;
  }
};

@Injectable()
export class LoginService {

  auth = new Observable<any>();
  constructor(private store: Store<AppStore>, private http: Http) {
    this.auth = store.select('auth');
  }

  attemptLogin(payload): Observable<any> {
    // let body = JSON.stringify({username, password});
    return this.http.post(Global.API_URL + '/login', payload)
      .map(response => response.headers.get('Authorization'));
      // .map(action => (
      //   { type: LoginActions.ATTEMPT_LOGIN, payload: action}))
      // .subscribe(action => {this.store.dispatch(action);
      // });
  }
}

Answer 1

当捕获到错误时，catch 返回的可观察对象用于继续链。返回的 observable 完成，完成效果并看到 ngrx 取消订阅效果。

将 map 和 catch 移动到 switchMap:

@Effect() login = this.actions
.ofType(LoginActions.ATTEMPT_LOGIN)
.map(toPayload)
.switchMap(payload => this.loginService.attemptLogin(payload)
  .map(response => new LoginActions.LoginSuccess(response))
  .catch(error => of(new LoginActions.LoginFailed(error)))
);

在 switchMap 内捕捉不会完成效果。

Answer 2

快乐之路场景：

错误场景：需要 reducer 来处理错误情况并在需要时向用户显示一些消息。

通过使用 rxjs/operators 中的 pipe 和 catchError，我们可以将两个（或所有）错误情况重新映射到一个 ErrorAction 中，然后我们可以直接在 effects 并进行副作用 ui 更改。

@Effect() login = this.actions
.ofType(LoginActions.ATTEMPT_LOGIN)
.map(toPayload)
.switchMap(payload => this.loginService.attemptLogin(payload)
  .map(response => new LoginActions.LoginSuccess(response))
  .catch(error => of(new LoginActions.LoginFailed(error)))
);

错误后可观察到 rx 损坏

Observable with rx broken after error

javascript

rxjs

ngrx-effects

angular

ngrx-store