Question

I have a WebPage on which I have to detect and prevent usage of Browser Refresh Button. (Now Please, dont suggest me Response.Redirect, I wont be able to use it in this scenario).

On looking at this page http://aspalliance.com/687_Preventing_Duplicate_Record_Insertion_on_Page_Refresh.4 I found the way. I’m planning to put this idea in a Control and place the control on every page.

Now that my page contains so many buttons and other controls. My concern is, If it is a refresh post… I dont want any events to get fired…

It will be tedious to go and check whether it is a refresh post in the beginning of every event as my entire application is almost built.

Any ideas that would help me.

• Raja

Including the below text for sake of more clarity :

Hi All, I hope a little misunderstanding… I dont want to stop user pressing the Refresh button… But all I want is to adjust my application’s response accordingly… Imagine a scenario, when user clicks BUTTON-A a popup window opens with another page. Now when the user comes back and clicks refresh button in the main window, the click event of BUTTON-A is fired again and popup window is opened again… In such scenario, I want to refresh the page as such, without opening the popup window. so, I need to stop ASP.NET from firing the click event of BUTTON-A (or any other similar buttons)

Answer 1

This is at least a starting point on how you can do it. I’m not sure all logic is 100%, but it is something to begin with…

protected void Page_Load(object sender, EventArgs e)
{
    foreach (Control control in Controls)
    {
        DisableEvent(control);
    }
}
protected void Page_PreRender(object sender, EventArgs e)
{
    foreach (Control control in Controls)
    {
        UpdateViewstate(control);
    }
}
private void DisableEvent(Control current)
{
    foreach (Control control in current.Controls)
    {
        if (control.GetType() == typeof(Button))
        {
            if (IsPostBack)
            {
                if (Session["update" + control.ID].ToString() != ViewState["update" + control.ID].ToString())
                {
                    RemoveClickEvent((Button)control);
                }
                else
                {
                    ((Button)control).Click += new EventHandler(Button_Disable);
                }
            }
            else
            {
                Session["update" + control.ID] = Server.UrlEncode(System.DateTime.Now.ToString());
            }
        }
        DisableEvent(control);
    }
}
private void UpdateViewstate(Control current)
{
    foreach (Control control in current.Controls)
    {
        if (control.GetType() == typeof(Button))
        {
            ViewState["update" + control.ID] = Session["update" + control.ID];
        }
        UpdateViewstate(control);
    }
}

void RemoveClickEvent(Button b) {
    System.Reflection.FieldInfo f1 = typeof(Button).GetField("EventClick", System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic); 
    object obj = f1.GetValue(b);
    System.Reflection.PropertyInfo pi = typeof(Button).GetProperty("Events", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
    System.ComponentModel.EventHandlerList list = (System.ComponentModel.EventHandlerList)pi.GetValue(b, null); 
    list.RemoveHandler(obj, list[obj]); 
}

protected void Button_Disable(object sender, EventArgs e)
{
    Button b = (Button)sender;
    Session["update" + b.ID] = Server.UrlEncode(System.DateTime.Now.ToString());
}