Web客戶端 - 異步操作是不允許在此背景下

Question

這是一個類庫，它獲取調用形式的網頁

try 
    { 
    System.Net.WebClient wc = WebAccess.GetWebClient(); 
    wc.UploadStringCompleted += new System.Net.UploadStringCompletedEventHandler(wc_UploadStringCompleted); 
    wc.UploadStringAsync(new Uri("http://" + MobileWLCUrl + urlCreateCacheAPI), GetJSONforGetMenuDetails(Id, MenuIds));      
    } 
catch (Exception ex) { EngineException.HandleException(ex); } 

void wc_UploadStringCompleted(object sender, System.Net.UploadStringCompletedEventArgs e) 
    { 
     string result = e.Result; 
     EngineException.CreateLog("Cache Created (for Menus: " + MenuIds + ") in API for LocationId: " + LocId); 
    } 

HIE傢伙，米試圖異步打這個URL，它是給我這個錯誤，任何幫助將appriciated。

Asynchronous operations are not allowed in this context. 
Page starting an asynchronous operation has to have the Async attribute set to true 
and an asynchronous operation can only be started on a page prior to PreRenderComplete event. 

at System.Web.AspNetSynchronizationContext.OperationStarted() 
at System.Net.WebClient.UploadStringAsync(Uri address, String method, String data, Object userToken) 
at System.Net.WebClient.UploadStringAsync(Uri address, String data) 

日Thnx ...

Answer 1

的Async="true"參數添加到@Page指令。

<%@ Page Async="true" ... %> 

西瓦尼，

您需要申請頁面（存儲在"http://" + MobileWLCUrl + urlCreateCacheAPI）本次變動叫下面的代碼：

wc.UploadStringAsync(new Uri("http://" + MobileWLCUrl + urlCreateCacheAPI), GetJSONforGetMenuDetails(Id, MenuIds));