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Data binding DropDownList user control within other user controls

Data binding DropDownList user control within other user controls

Post by Keith Geringe » Thu, 01 Aug 2002 03:00:06



I have a user control with a DataList object on it.  Within the
<EditItemTemplate> I have a user control that is a special DropDownList
object.

<asp:DataList ID="usercontrol1" Runat="Server"
    OnEditCommand="dlEdit_Command"
    OnUpdateCommand="dlUpdate_Command"
    OnDeleteCommand="dlDelete_Command"
    OnCancelCommand="dlCancel_Command">

<ItemTemplate>
    <asp:Button ID="btnEdit" Runat="server" Text="Edit" CommandName="Edit"
CommandArgument='<%# Container.DataItem("ID") %>' />
    <asp:Label ID="lblItem" Runat="server" Text='<%#
Container.DataItem("Line") %>' />
</ItemTemplate>
<EditItemTemplate>
    <mytag:MyDropDownList ID="ddlDropDownList" Runat="server"
SelectedValue='<%# Container.DataItem("Value") %>' />
</EditItemTemplate>
</asp:DataList>

My MyDropDownList component on page load calls a method that takes the
SelectedValue and sets the SelectedIndex of the DropDownList object in
MyDropDownList object.  When I do this I receive "Object reference not set
to an instance of an object" errors.  I've run tests and have found that the
SelectedValue property doesn't have a value either.  It acts like the object
doesn't exist yet.

What do I have to do?  What is the firing order of methods when I perform a
databind on the datalist?
Am I at least close?

Thanks, Keith Geringer

 
 
 
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Have web user control that contains four buttons and one a user clicks
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understand as page_load being called for parent web user control ) and
my database code never gets executed.  I load the child web user
controls dynamically, which is rendered from the use selecting a
particular button.  I have seen several responses to this, but nothing
that as provided answer.  I do understand that the child web user
control is no longer load.

Code:

private void Page_Load(object sender, System.EventArgs e)
{
if( Page.IsPostBack )
{
AddNewProject.Enabled = true;
AddNewComponent.Enabled = true;
DeleteComponent.Enabled = true;
RegisterUsers.Enabled = true;

private void DisplayControl( )
{
try
{
this.plcContent.Controls.Add( Page.LoadControl( "~/Administrators/" +
PageName + ".ascx" ) );
this.ShowSelection( PageName );
catch( Exception )
{
this.plcContent.Controls.Add( new System.Web.UI.LiteralControl(
"Invalid Selection!" ) );

private void ShowSelection( string sPage )
{
Button l_Button = (Button)this.FindControl( sPage );
l_Button.Enabled = false;

private void DeleteComponent_Click(object sender, System.EventArgs e)
{
PageName = "DeleteComponent";
DisplayControl( );

private void AddNewComponent_Click(object sender, System.EventArgs e)
{
PageName = "AddNewComponent";        
DisplayControl( );

private void AddNewProject_Click(object sender, System.EventArgs e)
{
PageName = "AddNewProject";
DisplayControl( );

private void RegisterUsers_Click(object sender, System.EventArgs e)
{
PageName = "RegisterUsers";          
DisplayControl( );

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