rxjs重新验证解决了

Question

我正在实施一个呼叫服务器的角服务。在每个通话中，我都需要传递一个持续约一分钟的令牌，然后我需要绘制响应以获取特定字段。因此，如果我的主电话失败了，我需要再次致电以获得令牌，等待响应然后重试我的第一个电话，是否有一种简单的方法来执行此操作？这是我的两种方法（它们都不属于属性）：

return this.http.post(url,
  firstCallText(this.token), { 
  responseType: 'text',
  headers
 })
  .pipe(
    map((xmlString: string) => {
      let asJson = this.xmlStringToJson(xmlString);
      return asJson["soap:Envelope"]["soap:Body"]["Response"]["#text"];
    }),
    catchError(async err=>{
      await this.http.post(url,
      getToken(),
      { 
        responseType: 'text',
        headers
      }).pipe(map((xmlString: string) => {
        let asJson = this.xmlStringToJson(xmlString);
        this.token = asJson["soap:Envelope"]["soap:Body"]["Response"]["Token"]["#text"];
      })).toPromise()
      return EMPTY
    }),
    retry()
  )

第一种方法失败了，因为在收到新令牌之前，请重试（）。 我的第二种方法是：

return this.http.post(url,
  firstCallText(this.token), { 
  responseType: 'text',
  headers
 })
  .pipe(
    map((xmlString: string) => {
      let asJson = this.xmlStringToJson(xmlString);
      return asJson["soap:Envelope"]["soap:Body"]["Response"]["#text"];
    }),
    retryWhen((errors) =>{
       this.http.post(url,
        getToken(),
        { 
          responseType: 'text',
          headers
        }).pipe(map((xmlString: string) => {
          let asJson = this.xmlStringToJson(xmlString);
          this.token = asJson["soap:Envelope"]["soap:Body"]["Response"]["Token"]["#text"];
        })).toPromise()
        return EMPTY          
    })
  )

第二种方法无法正确重试，我不想设置延迟，因为令牌呼叫可能更短或更长。

Answer 1

您在这里面临的问题是重试模仿源而没有错误，您实际上想处理错误本身。

因此，我的建议是将您的catherror opertaor扩展，以使其本身处理“失败”情况并恢复操作，以获取服务器的数据。

这是一个伪代码解决方案

// Answer for rxjs retryWhen promise is resolved  :https://stackoverflow.com/questions/72061841/rxjs-retrywhen-promise-is-resolved
const {interval, of, catchError} = rxjs;
const { switchMap, tap } = rxjs.operators;

// Start of Mock for your backednd
// requestToBeValidatedWithToken will either return success meassage whenver the token is valid or throw an error when the token has expired
let token = 0;
const requestToBeValidatedWithToken = () => {
  if (token < 0) {
    throw 'Expired token';
  }
  return of('Validated request suceeds');
};
// this mocks the refresh token logic
const fetchNewToken = () => {
  token = 3;
  return of('This refreshes the token');
};
// Timer that will invalidate your token
interval(1000).subscribe(() => {
  token--;
  if (token < 0) {
    console.log('BE message: Token has expired');
  }
});
// End of Mock for your backednd

// Start of rxjs pseudo code
// This will mock your base request stream, imaginge as the request is made each seconds
const methodInYourService = () => {
  const httpCall = interval(1000).pipe(
    switchMap(() => {
      return requestToBeValidatedWithToken();
    }),
    catchError((e) => {
      // This checks makes sure that only the "Expired token" case is handled so that you dont end in infinite loop
      if (e === 'Expired token') {
        console.log('Fire refresh token request', e);
        return fetchNewToken().pipe(
          tap(() => console.log('save your token as you recieve it')),
          switchMap(() => httpCall))
      }
      return e;
    })
  );
  return httpCall;
};

// This is the code inside your component, e.g. the place where you subscribe for the data
methodInYourService().subscribe(
  (x) => {
    console.log(x, 'fin');
  },
  (e) => {
    console.log('Will never come here, as we are handling the error');
  }
);

<script src="https://unpkg.com/rxjs@^7/dist/bundles/rxjs.umd.min.js"></script>

您可以在此处找到工作的伪代码解决方案
live xpemend xpemppect