将事件处理程序添加到转发器中的用户控件

Question

I have an asp.net web application. I have created a user control. The user control has an event handler that the parent page (.aspx file) can call. That .aspx page uses a repeater to make several of the user controls. If I put a single user control outside the repeater and add the event handler in Page_Load it works how I want it to. If I try the controls created in the repeater the do not call my events. I'll cut out as much as I can to make a somewhat simple code sample below.

Partial User Control .ascx.cs file:

    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();
    }

The markup of the user control that matters:

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

Here is the .aspx.cs part that works if I call it on Page_Load:

    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);
     }

This is what I am trying in the binding of the repeater that is not working:

    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);

        }
    }

This is the place holder for what the parent page .aspx should do when the event is raised by clicking the User Control:

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

Stuck on this for a while any and all help greatly appreciated!

Answer 1

Take a look at this ( https://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.repeater_events(v=vs.110).aspx ) to get an understanding of the Repeater's Event Life Cycle. Basically you need to wire a Web User Control's events at the time of the repeater items creation, not when it is being bound, which obviously happens after creation. The following code should work for you:

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);
    }
}