How to check is page is redirected from previous page or not in asp.net

Question

In Page 1 on button click I redirect the page to page 2 with msgid, and in page 2 in page load I check whether the previous page is valid. So i check (this.Page.PreviousPage != null) but this is always null and the page gets redirected to page 1. I am doing this so that no one can change the msgid in the url. How can I solve this issues. thanks

Page1:

  int msgid = Convert.ToInt32(Hidden_MsgID.Value);
    string url = "Page2.aspx?MsgID=" + msgid;
    Response.Redirect(url);      

Page2:

if (this.Page.PreviousPage != null)
                {
                }
                else
                {
                    Response.Redirect("Page1.aspx");
                }

instead of response.redirect I used server . transfer and it works Server.Transfer(string.Format("ResponseMetric.aspx?MsgID={0}", msgid));

Answer 1

PreviousPage does only work with Server.Transfer and/or cross-page-posting: http://msdn.microsoft.com/en-us/library/system.web.ui.page.previouspage.aspx

elements for your solution available here : work with this.Request.UrlReferrer

Answer 2

Maybe you can use a session variable to check if the flow is followed as well.. Before your redirect you can set

Session["PREVPAGE"] = "fooo.aspx";

And retrieve it in the page load of the second page..