在啓動時Gridview列數始終爲0

Question

下面的代碼在我的應用程序啓動時被調用。數據源確實有1個項目。但是，消息框永遠不會顯示。現在，當第一次繪製用戶界面時，gridview確實有一行。如果我在一個按鈕上再次調用代碼，請按下消息框顯示正確。這裏發生了什麼，我該如何解決它（我認爲它與線程有關，因爲radGridview尚未實際更新）？

C＃代碼綁定網格

// Bind list to gridview 
this.radGridViewFiles.BeginInvoke((MethodInvoker)(() => this.radGridViewFiles.DataSource = null)); 
this.radGridViewFiles.BeginInvoke((MethodInvoker)(() => this.radGridViewFiles.DataSource = MyGlobals.ListOfItemsToControl.Concat(MyGlobals.lstNewItems.Where(i => i.sItemRequestStatus == "Add").ToList()))); // 

if (radGridViewFiles.Columns.Count > 0) 
{ 
    RadMessageBox.Show(" This messagebox should show on startup but it does not - But if i call all this code again manually on a button press it does show ??? !!"); 

} 

Answer 1

要以異步方式綁定GridView的，這就是爲什麼當您檢查列計數它仍然是零。

我建議你在同一個線程中綁定它或等待異步操作完成。

按照您的要求，這裏是使用EndInvoke的代碼示例。雖然如果你用一種方法把它全部放在這裏 - 你不會從異步調用中獲得任何東西。

// You don't need this, so i commented it out. 
// it's excessive, you are going to overwrite this variable anyway 
// this.radGridViewFiles.BeginInvoke((MethodInvoker)(() =>this.radGridViewFiles.DataSource = null)); 

var asyncRes = this.radGridViewFiles.BeginInvoke((MethodInvoker)(() => this.radGridViewFiles.DataSource = MyGlobals.ListOfItemsToControl.Concat(MyGlobals.lstNewItems.Where(i => i.sItemRequestStatus == "Add").ToList()))); 

// This method blocks until previous operation is done 
// It's quite pointless. In real life you should call it somewhere from another thread 
// While qui thread is unblocked and displaying progress bar or something like this. 
this.radGridViewFiles.EndInvoke(asyncRes); 

// at this point, binding is complete 
if (radGridViewFiles.Columns.Count > 0) 
{ 
    RadMessageBox.Show(" This messagebox should show on startup but it does not - But if i call all this code again manually on a button press it does show ??? !!"); 
}