Add Events to Controls Nested in a Repeater ASP-C#

Question

I'm currently working with a repeater which has some number of drop down lists in it determined by how many items are databound to it. I wanted to add an event to each of these drop down lists in the scenario that a user changes the selected index.

Here is what I have for the repeater (Note that I am doing all of the databinding in the codebhind.):

        <ItemTemplate>
            <tr>
                <td>
                    <asp:DropDownList ID="DropDownList1" runat="server" Text='<%# Eval("Data") %>' AutoPostBack="True" OnTextChanged="TextChanged">
                        <asp:ListItem>Hello World</asp:ListItem>
                        <asp:ListItem>GoodBye Cruel World</asp:ListItem>
                    </asp:DropDownList>
                </td>
            </tr>
        </ItemTemplate>

        <FooterTemplate>
            </table>
        </FooterTemplate>
    </asp:Repeater>

I am setting the OnTextChanged event here, however I did some experimenting with using the different events. I found that my method will not run when I am using the OnTextChanged or OnSelectedIndexChanged events. However, if I use some other events like OnLoad or OnPreRender, the method I have it set to actually runs.

So in short, why is it that when I put this drop down list in the repeater only SOME of the events seem to work?

Answer 1

This is likely happening because you're rebinding the repeater in Page_Load. If you bind the repeater in CreateChildControls or OnPreRender, the OnTextChanged or OnSelectedIndexChanged events (both of which rely on ViewState) will fire correctly; otherwise, the control is rebound too early and no event is fired because no change is detected.

The other events are firing because they don't rely on ViewState.

Hope this helps.