Populating asp.net form from drop down list

Question

My Selected Index Changed from my drop down list, displays my list items, but will only display the top list item when any of the list items are selected to populate the form. It was working fine earlier today (perhaps I have changed something without noticing) and now it does not work.

 protected void ddlEdit_SelectedIndexChanged(object sender, EventArgs e)
{
    Book b = catalogueInstance.books[ddlEdit.SelectedIndex];
    txtID.Text = b.id.ToString();
    txtTitle.Text = b.title;
    txtAuthor.Text = b.author;
    txtYear.Text = b.year.ToString();
    txtPublisher.Text = b.publisher;
    txtISBN.Text = b.isbn;
}

Answer 1

If i was to guess this--You must be binding the DropDownList in the Page_Load event. Wrap that code inside Page.IsPostBack Check like below.

if (!Page.IsPostBack)
   {

      DropDownListBind();//here goes your binding code
   }