Varying the Output Cache by a Custom Function : Page Output Cache « Cache « ASP.NET Tutorial






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You create the custom function in the Global.asax file by overriding the GetVaryByCustomString() method. 

File: Global.asax

<%@ Application Language="C#" %>
<script runat="server">
    public override string GetVaryByCustomString(HttpContext context, string custom)
    {
        if (String.Compare(custom, "css") == 0)
        {
            return Request.Browser.SupportsCss.ToString();
        }
        return base.GetVaryByCustomString(context, custom);
    }

</script>

            
File: Default.aspx

<%@ Page Language="C#" %>
<%@ OutputCache Duration="3600" VaryByParam="none" VaryByCustom="css" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

    void Page_Load()
    {
        if (Request.Browser.SupportsCss)
            pnlCss.Visible = true;
        else
            pnlNotCss.Visible = true;
    }
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Vary By Custom</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

    <asp:Panel
        id="pnlCss"
        Visible="false"
        Runat="server">
        <span style="font-weight:bold">Hello!</span>
    </asp:Panel>

    <asp:Panel
        id="pnlNotCss"
        Visible="false"
        Runat="server">
        <b>Hello!</b>
    </asp:Panel>

    </div>
    </form>
</body>
</html>








13.9.Page Output Cache
13.9.1.You enable Page Output Caching by adding an <%@ OutputCache %> directive to a page.
13.9.2.OutputCache Duration="20" VaryByParam="None"
13.9.3.Varying the Output Cache by Parameter
13.9.4.Varying the Output Cache by Control
13.9.5.Varying the Output Cache by Header
13.9.6.Varying the Output Cache by Browser
13.9.7.Varying the Output Cache by a Custom Function
13.9.8.Manipulating the Page Output Cache Programmatically
13.9.9.Creating Page Output Cache Profiles