Angular get - 地图内的地图

Question

我正在尝试在地图中调用 API 方法，但从未进行过第二次 API 调用。没有控制台错误。

//This method is not being called - Not hitting the API method
this.getUserPermissions(localStorage.getItem('user_ref'));

只是想知道我是否不能在地图内调用地图？

下面是我的代码。

  public isAuthenticated() {

    if (!this.loggedIn)
      this.redirectToLogin();

    return this.httpClient.get<boolean>(`${this.settings.getApiSettings('uri')}/api/auth/IsTokenValid`, {
      params: { token: this.getToken }
    }).map( /// <<<=== use `map` here
      (response) => {

        if (response !== null) {

          var receivedToken = response["securityStamp"];
          var availableToken = localStorage.getItem('access_token');

           //Check if received a refreshed token. (tokens are refreshed every 15 minutes)
          if (receivedToken && receivedToken !== availableToken) {

            localStorage.removeItem('access_token');
            localStorage.setItem('access_token', response["securityStamp"]);

          }

           this.user_permissions = this.getUserPermissions(localStorage.getItem('user_ref'));


        }

        let data = response;
        if (data == null)
          return false;
        else
          return true;

      }
    );

  }

  getUserPermissions(user_ref) {

    if (!this.loggedIn)
      this.redirectToLogin();

    const httpParams: HttpParamsOptions = { userRef: "44C4D2F7-76A0-4714-B8CA-3123F607AC5A" } as HttpParamsOptions;

    const httpOptions = {
      params: new HttpParams(httpParams),
      headers: new HttpHeaders({
        'Content-Type': 'application/json',
        'Authorization': 'Bearer ' + this.getToken
      })
    };

    return this.httpClient.get<Array<any>>(`${this.settings.getApiSettings('uri')}/api/auth/GetUserPermissions`, httpOptions).map( /// <<<=== use `map` here
      (response) => {

        if (response["status"] == 401) {
          this.redirectToLogin();
        }
        else if (response["status"] < 200 || response["status"] >= 300) {
          throw new Error('This request has failed ' + response["status"]);
        }

        this.user_permissions = response;
        return response;
      }
    );

  }

Answer 1

当然，您可以在地图中调用地图，但这里您没有调用 API 的问题是因为您的方法“getUserPermissions”返回的是 Observable，而不是用户的数据。

我建议您按照响应式方法更改这部分的设计。

您可以阅读此link。

希望对你有帮助

Answer 2

您使用的是哪个版本的 Angular（更重要的是 rxjs）？

请记住，HttpClient 返回和 Observable（一个惰性的 observable，在您订阅它之前不会做任何事情）。

https://angular.io/guide/http

当您的 isAuthenticated 方法返回一个 HttpClient Get 方法时，您的 isAuthenticated 返回一个等待订阅的可观察对象。

订阅 HttpClient observable 将进行 http 调用，在收到响应时调用观察者的下一个处理程序，如果提供，还会调用 on complete 处理程序。我建议在这里阅读 Observables。 https://www.learnrxjs.io/

// Doing this will not do anything as the observable has not been subscribed to.
this.httpClient.get<boolean>(`...`);

// Subscribing to the HttpClient will make the request
this.httpClient.get<boolean>(`...`)
    .subscribe((response) => {

      // do something with the response

});

正如您所说的第一个 HttpCall 已创建，我假设您在调用时订阅了 isAuthenticated 方法？即

isAuthenticated().subscribe( (response) => {
 //
})

请注意，您的 getUserPermissions 还返回一个 HttpClient 方法（一个可观察的），但是当您调用它时 this.getUserPermissions(localStorage.getItem('user_ref')); 它永远不会被订阅，因此永远不会被调用。

要发起第二个请求，您必须订阅 getUserPermissions 调用，如下所示。

public isAuthenticated() {

    // ...

    return this.httpClient.get<boolean>('...').map(
      (response) => {

           // Subscribe to the second Http call

           this.getUserPermissions(localStorage.getItem('user_ref'))
             .subscribe( (response) => {
               // do something with the second
           })
       })
}

一些旁注； 从 rxjs v6 开始，您链接到 httpClient.get 方法的 map 运算符已被弃用，取而代之的是管道运算符。

见：https://github.com/ReactiveX/rxjs/blob/master/docs_app/content/guide/v6/migration.md

所以这个

this.httpClient.get<boolean>('...')
    .map( ... )
    .subscribe(...)

现在应该这样写：

this.httpClient.get<boolean>('...')
  .pipe(        // <- Pipe the operators
    map( ... ),
    map( ... )
  )
  .subscribe( ...)

尽管在最初的问题之外，我会考虑重构您的代码并使用可用的 rxjs/operators 来实现更好的流控制。

this.httpClient.get<boolean>('...')
    .pipe(       
      map(( response ) => {
        // some logic
        return something;
      }),
      map( (something) => localStorage.getItem('user_ref')),
      switchMap( (userRef) => this.getUserPermissions(userRef)), // <- switchMap to a new observable
    )
    .subscribe( (responseFromGetUserPermissions) => {
       // This value is now the return of getUserPermissions because of switchMap

    })

rxjs / observable 是一种非常强大的模式，我强烈建议您花大量时间学习如何充分利用它们。

问候 城野

Answer 3

这是因为.map() 函数不返回订阅，而是返回可观察对象。 如果您需要与来自 HttpClient 的 api 调用的响应进行交互，那么您需要订阅您正在调用的 .get() 或 .post() 方法。

这可能会满足您的需求，或者至少在控制台中记录以防请求失败。

firstUrl = `${this.settings.getApiSettings('uri')}/api/auth/IsTokenValid`;
secondUrl = `${this.settings.getApiSettings('uri')}/api/auth/GetUserPermissions`;

public isAuthenticated() {

    if (!this.loggedIn) this.redirectToLogin();
    return this.httpClient.get<boolean>(this.firstUrl, {params: {token: this.getToken}}).subscribe(
        (response) => {
            if (response !== null) {
                let receivedToken = response["securityStamp"];
                let availableToken = localStorage.getItem('access_token');
                if (receivedToken && receivedToken !== availableToken) {
                    localStorage.removeItem('access_token');
                    localStorage.setItem('access_token', response["securityStamp"]);
                }
                this.user_permissions = this.getUserPermissions(localStorage.getItem('user_ref'));
            }
            return response != null;
        },
        (error) => console.log(error)
    );
}

getUserPermissions(user_ref) {
    if (!this.loggedIn) this.redirectToLogin();
    const httpParams: HttpParamsOptions = {userRef: "44C4D2F7-76A0-4714-B8CA-3123F607AC5A"} as HttpParamsOptions;
    const httpOptions = {
        params: new HttpParams(httpParams),
        headers: new HttpHeaders({
            'Content-Type': 'application/json',
            'Authorization': 'Bearer ' + this.getToken
        })
    };
    return this.httpClient.get<Array<any>>(this.secondUrl, httpOptions).subscribe(
        (response) => {
            if (response["status"] == 401) {
                this.redirectToLogin();
            } else if (response["status"] < 200 || response["status"] >= 300) {
                throw new Error('This request has failed ' + response["status"]);
            }
            this.user_permissions = response;
            return response;
        },
        (error) => console.log(error)
    );
}