在重复器中为用户控件添加事件处理程序

Question

我有一个asp.net web应用程序。我创建了一个用户控件。该用户控件有一个事件处理程序，父页面（.aspx文件）可以调用。那个.aspx页面使用重复器来创建多个用户控件。如果我在Page_Load中放置一个单独的用户控件并添加事件处理程序，则它按照我的要求工作。如果我尝试在重复器中创建控件，则不会调用我的事件。以下是简化的代码示例： 部分用户控件.ascs.cs文件:

    public event EventHandler UserControlUploadButtonClicked;

    private void OnUserControlUploadButtonClick()
    {
        if (UserControlUploadButtonClicked != null)
        {
           //Makes it to this line if control is created outside repeater
           //controls created in repeater are null so this line not executed
           UserControlUploadButtonClicked(this, EventArgs.Empty);
        }
    }

    protected void TheButton_Click(object sender, EventArgs e)
    {
        // .... do stuff then fire off the event
        OnUserControlUploadButtonClick();
    }

用户控件的标记很重要：

<asp:ImageButton runat="server"  ID="imbUploadFile" ImageUrl="~/images/status_red.png" ToolTip="Upload File" onclick="TheButton_Click"  />

这是.aspx.cs部分的代码，如果我在Page_Load中调用它，它就可以正常工作：

    protected void Page_Load(object sender, EventArgs e)        
    {
        if (!IsPostBack)
        {
            LoadDDLs();\\Load drop down lists for filter for other UI stuff
        }
        \\This works!
        this.ucTest.UserControlUploadButtonClicked += new EventHandler(ManageUploader);
     }

这是我在重复器的绑定中尝试但无法正常工作的内容：

    protected void rptMonthlyFiles_ItemDataBound(Object Sender, RepeaterItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            DataRowView drv = e.Item.DataItem as DataRowView;
            //there are one of these for each month cut the rest out to make smaller code sample
            //Below gets DB info and sets up user control properly for UI based on business rules
            ((NRTWebApplication.UserControls.ucMonthlyFile2)e.Item.FindControl("ucOctMonthlyFile")).GetFileInfo();

            // This is how I am adding the event handler for each user control and it does not work like if done in Page_Load
            ((NRTWebApplication.UserControls.ucMonthlyFile2)e.Item.FindControl("ucOctMonthlyFile")).UserControlUploadButtonClicked += new EventHandler(ManageUploader);

        }
    }

当用户单击用户控件时，父页面.aspx 应执行的操作将显示在此占位符中：

    private void ManageUploader(object sender, EventArgs e)
    {
        // ... do something when event is fired
        this.labTest.Text = "After User Control Button Clicked";
    }

我卡在这里有一段时间了，非常感谢任何帮助！

- RichP

---

如果我的答案有帮助，请将其标记为答案。 - thewisegod

Answer 1

看一下这个链接 (https://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.repeater_events(v=vs.110).aspx)，了解Repeater的事件生命周期。基本上，您需要在重复项创建时连接Web用户控件的事件，而不是在绑定后连接，绑定显然是在创建后发生的。以下代码应该适用于您：

protected void rptMonthlyFiles_ItemCreated(Object Sender, RepeaterItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        DataRowView drv = e.Item.DataItem as DataRowView;
        //there are one of these for each month cut the rest out to make smaller code sample
        //Below gets DB info and sets up user control properly for UI based on business rules
        ((NRTWebApplication.UserControls.ucMonthlyFile2)e.Item.FindControl("ucOctMonthlyFile")).GetFileInfo();

        // This is how I am adding the event handler for each user control and it does not work like if done in Page_Load
        ((NRTWebApplication.UserControls.ucMonthlyFile2)e.Item.FindControl("ucOctMonthlyFile")).UserControlUploadButtonClicked += new EventHandler(ManageUploader);
    }
}

- thewisegod