更改用户控件上的属性

Question

I changed a public property in my web user control but the client doesn't see that change until I delete the user control and re-add it and then it sees the change.

I'm thinking to myself what if the user control is used in many places, will I have to do that to all of the pages? Certainly, I missing something?

Here's the code-behind of my webusercontrol:

public partial class ReportExporter : System.Web.UI.UserControl
{
    public IEnumerable<object> DataSource { get; set; }

    public String ExportFilename { get; set; }

    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void BtnExportCsv_Click(object sender, EventArgs e)
    {
        //Client needs to subscribe to this event and set the
        //DataSource property with IEnumerable. 
        //Todo: Find other ways to show this as a requirement.
        OnExportEvent(e);
        if (String.IsNullOrEmpty(ExportFilename))
            ExportFilename = "NeedToOverrideThisName";
        Response.Clear();
        Response.ContentType = "text/csv";
        Response.AddHeader("Content-Disposition", "attachment; filename=" + ExportFilename + ".csv");

        byte[] csvData = Utility.ToCsv(",", DataSource.ToList());
        Response.OutputStream.Write(csvData, 0, csvData.Length);
        HttpContext.Current.Response.End();
    }

    protected void BtnExportPdf_Click(object sender, EventArgs e)
    {

    }

    public event EventHandler ExportEvent;

    protected void OnExportEvent(EventArgs e)
    {
        if (ExportEvent != null)
        {
            ExportEvent(this, e);
        }
    }

}

All I did was change the property name for DataSource, it was AnyList.

Answer 1

If I understand, you could save the value of the property on the ViewState, for sample:

public String ExportFileName 
{ 
   get 
   {
       if (ViewState["ExportFileName_" + this.Id] == null) 
          return "default_name";

       return ViewState["ExportFileName_" + this.Id].ToString();
   }
   set
   {
       ViewState["ExportFileName_" + this.Id] = value;
   }
}

If you do something like this, you can have more than one user control instance on your page without problem, because the ViewState Key is indexed by the Id property of the user control.