Hi,

I have an Ajax enabled master and child page. In the child page,  I have two drop downs. One is visible and the other hidden. On Item change of first I have to show the second. In page load, if not postback, I am populating the second drop down and hiding it. On selectedindexchange of first I am showing the second drop down but values are not shown. Why is this happening? any idea? also the same issue exists with checkboxlist also.

 what am i doing wrong here? I tried to populate the listbox in index change of first also. it works but when i select it , i am not getting the selected value at all.

Can you post any related code?  So you are definitely wrapping binding code with not Page.IsPostBack, and you don't set EnableViewState="false" on that control or any parent control, right?

It's hard to tell so seeing the code and markup would help.

<ContentTemplate>

<asp:TableRow ID="trSave" runat=server Visible=false>

<asp:TableCell >Do you want to save the search?</asp:TableCell>

<asp:TableCell ><asp:DropDownList ID="ddlSearchDet" runat="server" OnSelectedIndexChanged="ddlSearchDet_SelectedIndexChanged" AutoPostBack=true EnableViewState=true >

<asp:ListItem></asp:ListItem>

<asp:ListItem Value="1" Text="Yes"></asp:ListItem>

<asp:ListItem Value="0" Text="No"></asp:ListItem>

</asp:TableCell>

</asp:TableRow>

</asp:Table>

<ContentTemplate>

<asp:Panel ID="pnlSearchDetails" runat=server Visible=false EnableViewState=true>

<tr>

<td colspan=4><asp:Label ID="lblError" runat=server ForeColor="Red" Visible=false></asp:Label></td>

</tr>

<tr>

<td>Search Name:</td>

<td colspan=3><asp:TextBox ID="txtSearchName" runat=server Columns=35 EnableViewState=true ></asp:TextBox></td>

</tr>

<tr>

<td>Description:</td>

<td colspan=3><asp:TextBox ID="txtDescription" runat=server TextMode="MultiLine" Columns=35 Rows=6 EnableViewState=true></asp:TextBox></td>

</tr>

<tr>

<td>Category:</td>

<td colspan=3><asp:DropDownList ID="ddlCategory" runat="server" OnSelectedIndexChanged="ddlCategory_SelectedIndexChanged" AutoPostBack=true>

</asp:DropDownList></td>

</tr>

<tr>

<td colspan=4>&nbsp;</td>

</tr>

</table>

</asp:UpdatePanel>

This is how the aspx is constructed..In code behind

I suggest tru to use CascadingDropDown from AJAXControlToolkit

CascadingDropDown is an ASP.NET AJAX extender that can be attached to an ASP.NET DropDownList control to get automatic population of a set of DropDownList controls. Each time the selection of one the DropDownList controls changes, the CascadingDropDown makes a call to a specified web service to retrieve the list of values for the next DropDownList in the set.

http://www.asp.net/AJAX/AjaxControlToolkit/Samples/CascadingDropDown/CascadingDropDown.aspx

Hey,

You could use that extender yes.  But I think the issue may be that the drop downs are in separate update panels; you have to manually call the Update method on the second update panel to update the UI on that panel, or put everything in one update panel...

Oh wait, I didn't see that you were nesting them; try removing the nesting as that's unnecessary...  just try the one and see.  If that doesn't work, post the selectedindexchanged event handler for the first drop down, and let's see what goes on there...

I removed the nesting also. as i posted earlier, the selected value is not coming now.

OK, so what does the related code method look like (fill method, selectedindexchanged)?

I have a button. In that click event, I am tracking the dropdown value to save.

ddlCategory.SelectValue

 I am having the same problem. I think when you hide the dropdown box, the viewstate is disabled and is not available after postback. I tested this with textbox and dropdown and it is happening only for dropdown.Can somebody please explain why this is happening and how do i avoid?

I am creating a dropdown dynamically and I cannot use hiddenfield for a workaround.

Thanks,

Gopal