啓用Silverlight的WCF服務重新調諧價值

Question

這是我的服務，檢查用戶名和密碼

[OperationContract] 

    public bool LoginCheck(string username, string password) 
    { 
     RoadTransDataContext db = new RoadTransDataContext(); 

     var _Pass = (from d in db.users where d.username == username select d.password).SingleOrDefault(); 

     if (_Pass == password) 
     { 
      return true; 
     } 
     else 
     { 
      return false; 
     } 
    } 

這是子窗口

private void LoginCheckCompleted(object sender, ServiceReference.LoginCheckCompletedEventArgs e) 
    { 
     _Log = e.Result; 
    } 

    private void OKButton_Click(object sender, RoutedEventArgs e) 
    { 
     ServiceReference.ServiceClient webservice = new ServiceReference.ServiceClient(); 

     webservice.LoginCheckCompleted += new EventHandler<ServiceReference.LoginCheckCompletedEventArgs>(LoginCheckCompleted); 
     webservice.LoginCheckAsync(txtUserName.Text, txtPassword.Password); 

     if (_Log == true) 
     { 
      this.DialogResult = true; 
      this.Close(); 
     } 
    } 

問題是，當OKButton_Click方法完成LoginCheckCompleted方法調用。所以如果它輸入正確的用戶名，傳遞並按下按鈕它什麼都不做，如果我再次單擊一次窗口關閉

Answer 1

Silverlight使用調用Web服務的異步模型，它需要一些時間來等待，直到返回響應。在你的例子中，分配_Log = e.Result;將被調用，讓我們假設，1-2秒後，而檢查if (_Log == true)將被稱爲immideately，當然之前的任務。

這就是爲什麼你應該把所有必要的代碼放在回調中，並在異步調用後刪除所有代碼。我已經爲您修復了這個問題：

private void LoginCheckCompleted(object sender, ServiceReference.LoginCheckCompletedEventArgs e) 
{ 
    _Log = e.Result; 

    if (_Log == true) 
    { 
     this.DialogResult = true; 
     this.Close(); 
    } 
} 

private void OKButton_Click(object sender, RoutedEventArgs e) 
{ 
    ServiceReference.ServiceClient webservice = new ServiceReference.ServiceClient(); 

    webservice.LoginCheckCompleted += new EventHandler<ServiceReference.LoginCheckCompletedEventArgs>(LoginCheckCompleted); 
    webservice.LoginCheckAsync(txtUserName.Text, txtPassword.Password); 
}