Web Form Parameter Passing

Last Updated: 2001

Post data is read-only on the server. Thus if we want to change the value of post data on the server before passing it on to another form we cannot.

MSDN describes a complex method of passing properties between forms. That method has a major drawback in that the called form has to have a reference to the calling form in the aspx and a cast to that form in the aspx.cs. If you want to call the same form from two places, it simply isn't possible.

However, if we use an interface, we can:

ObjParams.cs
interface IObjParams {
    string GetParam1();
}

MyCallingForm.aspx.cs:
public class MyCallingForm : System.Web.UI.Page, IObjParams { ....
...
    public string GetParam1() {
        return txt1.Value;
    }
...
    private void Button1_Click(object sender, System.EventArgs e) {
        txt1.Value="1234";
        Server.Transfer("MyCalledForm.aspx", true);
    }
}

MyCalledForm.aspx.cs:
....
    if (!Page.IsPostBack) {
        string res=((IObjParams) Context.Handler).GetParam1();
....