C# 访问位于用户控件中的 DropDownList 项值

Question

I have aa generic control called dropdownlist.ascx that populates it's ListItems based on a XML document and a property that I pass to this control.

This control is used multiple times on the same aspx page. I have no problem casting this control as a DropDownList control in the Page_Load event of the aspx page, however when I want to set the SelectedValues of this control on the Page_Load event of the aspx page it doesn't work as the Items.Count value is 0.

I assume there are some Page Lifecyle issues going on here.

Control on page.aspx

<triangle:DDLResponse ID="ddlHeight" runat="server" CssClass="dropdownlist ddlregister" responseId="height" mode="dropdownlist" />

Codebehind on page.aspx

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        UserProfile profile = controls_session.profile;

        DropDownList _ddlHeight = (DropDownList)ddlHeight.FindControl("dropdownlist");

        _ddlHeight.SelectedValue = profile.Height;          

    }
}

The List Items of ddlHeight render without issue.

Anyone have any idea or solution to this?

Thanks,

Answer 1

Try to set the SelectedValue in Page_PreRender event. It will work.