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The VaryByParam attribute causes a new instance of a page to be cached when a different parameter is passed to the page.
File: Master.aspx
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Master</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:GridView
id="grdProducts"
DataSourceID="srcProducts"
AutoGenerateColumns="false"
ShowHeader="false"
GridLines="none"
Runat="server">
<Columns>
<asp:HyperLinkField
DataTextField="Title"
DataNavigateUrlFields="Id"
DataNavigateUrlFormatString="~/Details.aspx?id={0}" />
</Columns>
</asp:GridView>
<asp:SqlDataSource
id="srcProducts"
ConnectionString="<%$ ConnectionStrings:Products %>"
SelectCommand="SELECT Id,Title FROM Products"
Runat="server" />
</div>
</form>
</body>
</html>
File: Details.aspx
<%@ Page Language="C#" %>
<%@ OutputCache Duration="3600" VaryByParam="id" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Details</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<%= DateTime.Now.ToString("T") %>
<hr />
<asp:DetailsView
id="dtlProduct"
DataSourceID="srcProducts"
Runat="server" />
<asp:SqlDataSource
id="srcProducts"
ConnectionString="<%$ ConnectionStrings:Products %>"
SelectCommand="SELECT * FROM Products
WHERE Id=@Id"
Runat="server">
<SelectParameters>
<asp:QueryStringParameter
Name="Id"
Type="int32"
QueryStringField="Id" />
</SelectParameters>
</asp:SqlDataSource>
</div>
</form>
</body>
</html>
You can assign two special values to the VaryByParam attribute:
none: causes any query string or form parameters to be ignored.
*: caches a new cached version whenever there is a change in query string or form parameter passed to the page.
You can assign a semicolon-delimited list of parameters to the VaryByParam attribute.
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