Custom Control - DropDownList losing Items

[fwirtanen]

I am building a custom composite control consisting of two drop downs,
with parent/child dependancy.

The child dropdownlist is updated through client callback when the
parent index changes.

An 'All' list item is added to the child dropdown during the
CreateControlHe irarchy(bool useDataSource) method.

Somewhere between the CreateControlHe irarchy method executing and the
Render event the added ListItem disappears. This only happens on the
first page load. Refreshing the browser or doing a postback, everything
works fine.

I put breakpoints all over the code, nothing that touches ddlChild is
executing between the OnDataBinding & Render events.

I must be missing something.

Anyone have any ideas?

Thx.

Here is the relevant sections of the code

protected void CreateControlHe irarchy(bool useDataSource)
{
ddl1 = new DropDownList();
ddlChild = new DropDownList();

ddlParent.ID = this.UniqueID + "parent";
ddlChild.ID = this.UniqueID + "child";

//viewstate gets out of sync on child due to callbacks, so
don't use it
ddlChild.Enable ViewState = false;

ddlParent.Attri butes.Add("onch ange",
"UpdateChild(th is.options[this.selectedIn dex].value,'parent' );");
if (useDataSource)
{
//bind datasource to Parent - maintained by viewstate
ddlParent.DataS ource = ParentDataSourc e;
ddlParent.DataT extField = ParentDataTextF ield;
ddlParent.DataV alueField = ParentDataValue Field;

if (objParentList != null)
ddlParent.DataB ind();
}

//always reload & bind child, viewstate is disabled
if (ChildDataSourc e != null)
{
ddlChild.DataSo urce = ChildDataSource ;
ddlChild.DataTe xtField = ChildDataTextFi eld;
ddlChild.DataVa lueField = ChildDataValueF ield;
ddlChild.DataBi nd();

}

//**** ListItem added here - stepping through code in debug shows
the ListItem has been added ****

if (hasAllItem)
{
ddlChild.Items. Insert(0, new
ListItem(AllChi ldItemText,AllC hildItemValue)) ;
}

Label lblParent = new Label();
lblParent.Text = ParentTitle;
lblParent.Enabl eViewState = false;
lblParent.Width = labelWidth;

Label lblChild = new Label();
lblChild.Text = ChildTitle;
lblChild.Enable ViewState = false;
lblChild.Width = labelWidth;

ddlParent.Width = dropDownWidth;
ddlChild.Width = dropDownWidth;

Controls.Add(lb lParent);
Controls.Add(dd lParent);
Controls.Add(ne w LiteralControl( "<br>"));
Controls.Add(lb lChild);
Controls.Add(dd lChild);

RegisterClientS ideScripts();
}

protected override void Render(HtmlText Writer writer)
{
//******* Watch on ddlChild.Items shows added ListItem has
disappeared ********

EnsureChildCont rols();
base.Render(wri ter);
}

protected override void CreateChildCont rols()
{
//This event doesn't fire on first page load
Controls.Clear( );
CreateControlHe irarchy(false);

}

protected override void OnDataBinding(E ventArgs e)
{
base.OnDataBind ing(e);

Controls.Clear( );
CreateControlHe irarchy(true);
if (HasChildViewSt ate)
{
ClearChildViewS tate();
}
ChildControlsCr eated = true;
if (!IsTrackingVie wState)
{
TrackViewState( );
}

//******* Watch on ddlChild.Items shows added ListItem is still here
when this event exits********

}