Assigning an Event to a Custom Control Inside a Repeater Control

Question

I have a Repeater control, which in some of its cells contains a UserControl that contains a DropDownList. In the ItemDataBound event of the Repeater element, I assign the DropDownList event as follows:

protected void MyRepeater_ItemDataBound(object sender, RepeaterItemEventArgs e)  
{  
...  
MyControl myControl = (MyControl)e.Item.FindControl("MyControl01");  
myControl.DataSource = myObject;  
myControl.DataBind();  
myControl.DropDownList.SelectedItemChange += MyMethod_SelectedIndexChanged;  
myControl.DropDownList.AutoPostBack = true;  
....  
}  

protected void MyMethod_SelectedIndexChanged(object sender, EventArgs e)  
{  
//Do something.  
}

The event never fires. Please, I need some help.

Answer 1

Your event is not created in PostBack because your event handler was not attached (it is attached only during the iteration of the page life cycle, when your relay is a database binding).

If you attach an event handler declaratively in the markup, for example:

<asp:Repeater ID="Repeater1" runat="server">
     <ItemTemplate>
         <asp:DropDownList ID="DropDownList1" runat="server" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged" />
    </ItemTemplate>
</asp:Repeater>

PostBacks.

Answer 2

, , :

• MyRepeater , ! IsPostBack.
• Bind MyRepeater OnInit.

1) , , ASP.NET , .

2) OnInit, OnLoad.

Answer 3

, .

, ItemTemplate

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="ListBoxContainer.ascx.cs" Inherits="OAAF.Common.ListBoxContainer" %>

<asp:ListBox ID="lstFromControl" runat="server" Rows="1" DataTextField="Text" DataValueField="Id" OnSelectedIndexChanged="LstFromControl_SelectedIndexChanged" AutoPostBack="true" />

, ItemTemplate

public partial class ListBoxContainer : System.Web.UI.UserControl
{
    //declare the event using EventHandler<T>
    public event EventHandler<EventArgs> ListBox_SelectedIndexChanged;

    protected void Page_Load(object sender, EventArgs e)
    {
    }

    protected void LstFromControl_SelectedIndexChanged(object sender, EventArgs e)
    {
        //fire event: the check for null sees if the delegate is subscribed to
        if (ListBox_SelectedIndexChanged != null)
        {
            ListBox_SelectedIndexChanged(sender, e);
        }
    }
}

, , : ListBox_SelectedIndexChanged. , EventArgs.

, , :

<asp:Repeater ID="rptTest" runat="server">
<ItemTemplate>
    <br />
    <ctrl:wucListBox ID="listBoxControl" runat="server" OnListBox_SelectedIndexChanged="ListBoxControl_SelectedIndexChanged" />
</ItemTemplate>    
</asp:Repeater>

, ,

<%@ Register Src="~/Common/ListBoxContainer.ascx" TagName="wucListBox" TagPrefix="ctrl" %>

ListBox_SelectedIndexChanged, , , , .

    protected void ListBoxControl_SelectedIndexChanged(object sender, EventArgs e)
    {
        //some code
    }