Asynchronous RxJS等待第二个可观测值，然后在出现错误时重试原始可观测值-TypeScript/Angular 2

我是Angular 2、TypeScript和RxJS的新手，我正在创建一个利用Salesforce Ajax工具包连接库的简单应用程序

我试图编写一个处理程序，以便在调用connections库中的方法时捕获令牌何时过期。我已经创建了一个服务，它基本上包装了连接库以使用可观察的对象。例如，如果我们查看插入函数，我已经创建了自己的包装函数：

 public insert(object: sforce.SObject): Observable<any> {
   return new Observable(observer => {
   // successfully inserted the record
   let insertSuccess = (result) => {
     observer.next(result);
     observer.complete();
    }

    // An error occured inserting the record
    let insertError = (result) => {
      // This does not work yet
      if (result.faultcode.indexOf('INVALID_SESSION_ID') != -1) {
        this.refreshToken();
      }
      else {
          observer.error(result);
      }
    }

    let callback = { onSuccess: insertSuccess, onFailure: insertError };
    sforce.connection.create([object], callback);
  });
}

我基本上希望原始的

insert

函数等待

refreshtToken

完成。如果成功，我希望再次重试相同的插入，否则我希望原始的插入可观察调用

observer.error

---

我已经研究了

retry

和

retryWhen

，但是在等待

refreshttoken（）

函数完成之前，我还没有弄清楚如何实现它。对此问题的任何指导或建议将不胜感激。提前谢谢。

操作员接受一个处理错误和源代码的函数。这意味着，如果捕获到错误，可以在

catch

块中确定是否要重新订阅原始源：

 public insert(object: sforce.SObject): Observable<any> {
   return new Observable(observer => {
   // successfully inserted the record
   let insertSuccess = (result) => {
     observer.next(result);
     observer.complete();
    }

    // An error occured inserting the record
    let insertError = (result) => observer.error(result);


    let callback = { onSuccess: insertSuccess, onFailure: insertError };
    sforce.connection.create([object], callback);
  }).catch((err, source) => {
     if (err.faultcode.indexOf('INVALID_SESSION_ID') != -1) {
        //This waits for the refresh to complete and then resubscribes
        //to the source
        //If the refresh errors then it will skip the resubscribe
        return this.refreshToken().flatMapTo(source);
     }
     //Non-authentication error
     return Observable.throw(err);
  });
}

---

谢谢你的回答@paulpdaniels！你能解释一下tap是做什么的吗

this.loginService.login

返回一个

http.post

。我收到错误

this.loginService.login（…）。tap不是一个函数

tap

对流中的事件执行副作用，同时仍让它们通过。您很可能需要使用

import'rxjs/add/operator/tap'

 public insert(object: sforce.SObject): Observable<any> {
   return new Observable(observer => {
   // successfully inserted the record
   let insertSuccess = (result) => {
     observer.next(result);
     observer.complete();
    }

    // An error occured inserting the record
    let insertError = (result) => observer.error(result);


    let callback = { onSuccess: insertSuccess, onFailure: insertError };
    sforce.connection.create([object], callback);
  }).catch((err, source) => {
     if (err.faultcode.indexOf('INVALID_SESSION_ID') != -1) {
        //This waits for the refresh to complete and then resubscribes
        //to the source
        //If the refresh errors then it will skip the resubscribe
        return this.refreshToken().flatMapTo(source);
     }
     //Non-authentication error
     return Observable.throw(err);
  });
}

 public refreshToken(): Observable<any> {
    return this.loginService.login()
      .tap(response => {
        Globals.SESSION_TOKEN = response.access_token;

        //initialize the salesforce connection 
        this.init(Globals.SESSION_TOKEN, this.loginService.AuthParams.SOAP_URL);
      });
}