DropDownList SelectedValue Problems

[Guest]

Forget about the controlParameter for the moment, for testing purposes i have
created the following

Markup:

<asp:Table ID="tblSelectRoute" runat="server" CssClass="asp-table">
<asp:TableRow>
<asp:TableCell CssClass="asp-table-header">Select
Route<asp:Label ID="lblTest" runat="server"></asp:Label>
</asp:TableCell>
<asp:TableCell CssClass="asp-table-cells">
<aspropDownList ID="DDLSelectRoute" runat="server"
AutoPostBack="True" DataSourceID="SDSRoutesList" DataTextField="Route"
DataValueField="RouteID" CausesValidation="True"
OnSelectedIndexChanged="DDLSelectRoute_SelectedIndexChanged">
</aspropDownList>
</asp:TableCell>
</asp:TableRow>
</asp:Table>

Code in the PageLoad event handler:

lblTest.Text = DDLSelectRoute.SelectedValue;

For some reason i cannot fathom, the label control is blank untill the value
in the DDL is changed. The HTML rendered to the browser shows thus

<select name="ctl00$ContentPlaceHolder1$DDLSelectRoute"
onchange="javascript:setTimeout('WebForm_DoPostBackWithOptions(new
WebForm_PostBackOptions("ctl00$ContentPlaceHolder1$DDLSelectRoute", "", true,
"", "", false, true))', 0)" id="ctl00_ContentPlaceHolder1_DDLSelectRoute">
<option selected="selected" value="1">1 - Test</option>
<option value="2">2 - Test</option>

<option value="3">3 - Test</option>

So the first item is selected.

If i add DDLSelectRoute.SelectedIndex = 4; at the begining of the pageload
event handler then the selected index is chyanged but the label control is
still blank until i change the value in the DDL.

If i replace lblTest.Text = DDLSelectRoute.SelectedValue; with lblTest.Text
= DDLSelectRoute.SelectedItem.Value; i get an "Object reference not set to an
instance of an object" exception. But if i then cut lblTest.Text =
DDLSelectRoute.SelectedItem.Value; from the page load event and then paste it
inro the SelectedIndexChanged event handler for the DDL as soon as you change
the DDL then the label control is updated.

I am totally puzzled, it is acting as if the SelectedValue is not set until
you change the DDL at least once.

 

[Guest]

Ignore the above post, the problem was cause by the fact that the
DropDownList ahnd't been data bound yet during the PageLoad event.