等待异步方法完成

Question

我正在尝试创建一个调用http请求的方法。如果请求返回401错误，我想重新登录并再次尝试请求。我的方法如下所示：

return this.http.post(url, this.cleanData(body), this.appendHttpHeaders(options)) 
     .map(response => response) 
     .catch(error => { 
      if (error.status === 401) { 
       this.loginService.login(true).then(() => { 
        console.log("login should be finished: " + this.loginService.isLoggedIn()); 
        return this.http.post(url, this.cleanData(body), this.appendHttpHeaders(options)) 
         .map(response => response); 
       }) 
      } else { 
       this.errorReportingService.reportHttpError(error); 
       return Observable.throw(error); 
      } 
     }); 

public login(forceLogin = false, loginCallback:() => any = null): Promise<String> { 
    ... 
    console.log(1); 
    return new Promise((resolve, reject) => { 
     console.log(2); 
     this.popupLogin(loginCallback).then((result) => { 
      console.log(11); 
      resolve(); 
     }) 
    }).then(() => { 
     return new Promise((resolve, reject) => { 
      console.log(12); 
      resolve(); 
     }) 
    }) 
} 

private popupLogin(loginCallback:() => any = null): Promise<String> { 
    ... 
    console.log(3); 
    return new Promise((resolve, reject) => { 
     console.log(4); 
     this.handleLoginPopupFeedback(loginPopupHandle, loginCallback).then((result)=> { 
      console.log(9); 
      resolve(); 
     }) 
    }).then(() => { 
     return new Promise((resolve, reject) => { 
      console.log(10); 
      resolve("ok"); 
     }) 
    }) 
} 


private handleLoginPopupFeedback(loginPopupHandle: Window, loginCallback:() => any = null): Promise<string> { 
    ... 
    } else { 
     // ...popup is accessible, check values 
     let loginSuccessElement = loginPopupContent.getElementById('trucareOAuthLoginSuccess'); 
     let loginFailureElement = loginPopupContent.getElementById('trucareOAuthLoginFailure'); 

     if (!loginPopupHandle.closed && 
      (loginSuccessElement === null || loginSuccessElement === undefined) && 
      (loginFailureElement === null || loginFailureElement === undefined) 
     ) { 

      console.log(5); 
      return new Promise((resolve, reject) => { 
       console.log(6); 
       setTimeout(() => { 
        console.log(7); 
        this.handleLoginPopupFeedback(loginPopupHandle, loginCallback).then((result) => { 
         console.log(8); 
         resolve(); 
        }, 500) 
       }) 
      }); 
     } 
     ... 
    } 

    return Promise.resolve("4"); 
} 

问题是登录调用是异步的。有没有办法等待loginService.login（）完成，然后再次尝试请求？

编辑：根据注释修改代码，但调用仍然不会重复，即使是console.log正在记录。但是，我甚至没有看到网络插口调用浏览器

Answer 1

你可以使用retryWhen()运营商，它可以让你等待，直到另一个观察的发射重试初始观察到的在错误的情况下，例如：

return this.http.post(url, body...) 
    .retryWhen(errors => this.loginService.login(true)) 
    .map(res => res.json()); 

Answer 2

刚刚尝试retryWhen：

.retryWhen(errors => { 
    return this.loginService.login(true).zip(errors).flatMap(([isLoggedIn, error]) => { 
     if(!isLoggedIn || error.status !== 401) { 
     return Observable.throw(error); 
     } 
     return Observable.of(true); 
    }) 
    }) 

Answer 3

当我需要等到一定条件满足我使用这个功能我编写的名为ploop（承诺循环）运行，并重新运行一个承诺：

// fn  : function that should return a promise. 
// args : the arguments that should be passed to fn. 
// donefn : function that should check the result of the promise 
// and return true to indicate whether ploop should stop or not. 
// promise: A promise value that is used internally by ploop and should never 
// be passed in by the caller of ploop. 
var ploop = function(fn, args, donefn, promise) { 
    return (promise || Promise.resolve(true))  
     .then(function() { 
      return(fn.apply(null, args)); 
     }) 
     .then(function(result) { 
     var finished = donefn(result); 
     if(finished === true){ 
      return result; 
     } else { 
      return ploop(fn, args, donefn, promise); 
     } 
    }); 
}; 

这里是使用它的例子：

// Function that returns a promise 
var searchForNumber = function(number) { 
    return new Promise(function(resolve, reject) { 
     setTimeout(function() { 
     var min = 1; 
     var max = 10; 
     var val = Math.floor(Math.random()*(max-min+1)+min); 

     console.log('Value is: ' + val.toString());   

     return resolve(val);   
     }, 1000); 
    }); 
}; 

var searchFor = 4; 

var donefn = function(result) { 
    return result == searchFor; 
}; 

console.log('Searching for: ' + searchFor); 
ploop(searchForNumber, [searchFor], donefn) 
    .then(function(val) { 
    console.log('Finally found! ' + val.toString()); 
    process.exit(0); 
    }) 
    .catch(function(err) { 
    process.exit(1); 
    }); 

由于您的http.get返回你应该能够在通过它与你的参数传递给ploop沿着一个承诺。您完成的功能可以检查结果中的迭代或其他条件，以确定是否继续运行诺言。

下面是一个例子：http://jsbin.com/xefutos/4/edit?js,console