Question

I am trying to access a DropDownList within a div after I add them from the code-behind.
If I add DropDownList to my .aspx page like this:

<div id="FiltersDiv" runat="server">
                <asp:DropDownList ID="DropDownListMenu" runat="server" 
                      DataTextField="name" DataValueField="id"
                    AutoPostBack="true" 
                      onselectedindexchanged="DropDownListMenu_SelectedIndexChanged" >
                </asp:DropDownList>

I can get access in any event

protected void AddButton_Click(object sender, EventArgs e)
 {
   var dl = addProductLocationFiltersDiv.Controls.OfType<DropDownList>();
 }

but not if I add from code

var ddl = new DropDownList();
 ddl.DataSource = flist;
 ddl.DataTextField = "name";
 ddl.DataValueField = "id";
 ddl.DataBind();
 FiltersDiv.Controls.Add(ddl);

I need to add several DropDownList’s and I do not now how many will be. So, I need to looping thru.
Did I miss some attribute or how I need to do it?

Answer 1

When you add a control via code, you access it through the variable name.

If you need access to several of these, consider putting then in a List<DropDownList> (or List<Control> if you have different types of controls).

If you need to share these across methods in your code behind, use a field instead of a local variable.

Note, that due to how the ASP.NET page lifecycle works, you will probably need to recreate these on every postback, otherwise you will not be able to access them. The best location to recreate such controls dynamically is in the OnInit handler.