从此页面访问其他页面控件

Question

Page 1 - Ticket.aspx , DropDownList1 , ModalPopUpextender with id mpe

Page 2 - Customer.aspx , btnSave

The index change event of dropdown will pop up mpe which has an iframe . This iframe loads Customer.aspx .

I am trying to access page1 controls in the button click event, but unable to.

Customer.aspx.cs:

protected void btnSave_Click()
{
  Ticket page = new Ticket();
  ModalPopUpExtender mpe = (ModalPopUpExtender)page.FindControl("mpe");
  DropDownList ddl = (DropDownList)page.FindControl("DropDownList1");

  //error here - Object reference not set to an instance

    mpe.hide();

    ddl.selectedindex=0;
}

Why is this not working. Using a Session variable should work right?

Answer 1

You may use Server.Transefer instead of Response.Redirect and then you can find the control in the current page. Like:

TextBox tb = (TextBox)PreviousPage.FindControl("textbox1");

EDIT:

if (Page.PreviousPage != null)
{
    DropDownList ddl1 = 
        (DropDownList)Page.PreviousPage.FindControl("DropDownList1");
    if (ddl1 != null)
    {
        Label1.Text = ddl1.SelectedItem.Text; //your logic
    }
}

Answer 2

What you are trying may not be doable from the server side, but it can be easily be done with a little javascript. Here is a link where you can get a working piece of code.

Hope this helps.