How to prevent duplicate insert or other action when user refresh browser.

1月16日

How to prevent Browser Refresh

From my live space.

This article is about the solution  of duplicate action about the Browser Refresh after postback.

Why the browser refresh will cause the old data to post again.

The page refresh or backwards is a sort of browser internal operation without any notification.

The browser caches the latest request it had served, including viewstate, when you refresh the browser,

it will reissues the data.

Solution:

Reference:

http://aspalliance.com/687_Preventing_Duplicate_Record_Insertion_on_Page_Refresh.all#Page4

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnvs05/html/bedrockaspnet.asp

My Solution: since viewstate will be cached old but session not, we can indicate the browser action by this difference.

if the value of viewstate does not equal to the value of session, then it's refresh action

Create a base page class, then all sub-class can inherit the functionality.

in base page class constructor:

Constructor#region Constructor

public BasePage()

{

this.Page.PreRender += new EventHandler(Page_PreRender);

}

#endregion

in Page_PreRender method:

Method: Page_PreRender#region Method: Page_PreRender
void Page_PreRender(object sender, EventArgs e)
{
     if (IsPostBack == false)
     {
         SetActionTick();
     }
     ViewState["ActionTick"] = Session["ActionTick"];
}
#endregion

In SetActionTick() to set the timestamp of this action.

Method: SetActionTick#region Method: SetActionTick
  protected void SetActionTick()
  {
      Session["ActionTick"] = Server.UrlEncode(DateTime.Now.ToString("yyyyMMddhhmmss"));
  }
  #endregion

The property IsRefresh

Property: IsRefresh#region Property: IsRefresh
protected bool IsRefresh
{
    get
    {
        //if (Session["RefreshTick"] == null)
        //{
        //    return false;
        //}
        if (ViewState["ActionTick"] as string == Session["ActionTick"] as string)
        {
            SetActionTick();
            return false;
        }
        return true;
    }
}
#endregion

So the sub-page class can use this property.

if (IsRefresh == false)

// Insert