How to Execute Base Class's ExtractPageData() Before Implementors's ExtractPageData()?
- by DaveDev
I have the following page 
public partial class GenericOfflineCommentary : OfflineFactsheetBase
{
}
where OfflineFactsheetBase is defined as
    public class OfflineFactsheetBase : System.Web.UI.Page
    {
        public OfflineFactsheetBase()
        {
            this.Load += new EventHandler(this.Page_Load);
            this.PreInit += new EventHandler(this.Page_PreInit);
        }
    protected void Page_PreInit(object sender, EventArgs e)
    {
        if (Request.QueryString["data"] != null)
        {
            this.PageData = StringCompressor.DecompressString(Request.QueryString["data"]);
            this.ExtractPageData();
        }
    }
}
OfflineFactsheetBase has the following virtual method:
public virtual void ExtractPageData()
{
    // get stuff relevant to all pages that impmement OfflineFactsheetBase 
}
which is implemented in all pages that impmement OfflineFactsheetBase as follows:
public partial class GenericOfflineCommentary : OfflineFactsheetBase
{
    public override void ExtractPageData()
    {
            // get stuff relevant to an OfflineCommentary page.
    }
}
Currently, only GenericOfflineCommentary's ExtractPageData() is firing. How can I modify this to first run OfflineFactsheetBase's ExtractPageData() and then GenericOfflineCommentary's?