HttpResponse.AddCacheDependency(CacheDependency[]) Method

Reference

Definition

Namespace:: System.Web

Assembly:: System.Web.dll

Important

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Associates a set of cache dependencies with the response to facilitate invalidation of the response if it is stored in the output cache and the specified dependencies change.

public:
 void AddCacheDependency(... cli::array <System::Web::Caching::CacheDependency ^> ^ dependencies);

public void AddCacheDependency (params System.Web.Caching.CacheDependency[] dependencies);

member this.AddCacheDependency : System.Web.Caching.CacheDependency[] -> unit

Public Sub AddCacheDependency (ParamArray dependencies As CacheDependency())

Parameters

dependencies: CacheDependency[]

A file, cache key, or CacheDependency to add to the list of application dependencies.

Exceptions

ArgumentNullException

The dependencies parameter is null.

InvalidOperationException

This method was called too late in the cache processing pipeline, after the cached response was already created.

Examples

The following example demonstrates how to create a cache dependency by using the AddCacheDependency method and a CacheDependency object.

<%@ Page Language="C#" %>
<%@ outputcache duration="30" varybyparam="none" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="Server">
    private void Page_Load(object sender, System.EventArgs e)
    {
        // Create a Cache Dependency 
        // using a CacheDependency object.
        CacheDependency authorsDependency = new CacheDependency("authors.xml");


        // Make the page invalid if either of the
        // cached items change or expire.        
        Response.AddCacheDependency(authorsDependency);

        // Display the current time for cache reference
        lblOutputCacheMsg.Text = DateTime.Now.ToString();
    }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>Cache Dependencies</title> 
</head>
<body>
    <form id="Form1" method="post" runat="server">
        <table>
            <tbody>
                <tr>
                    <td style="WIDTH: 118px">
                        The page was generated at:</td>
                    <td>
                        <asp:Label id="lblOutputCacheMsg" runat="server"></asp:Label>
                    </td>
                </tr>
            </tbody>
        </table>
    </form>
</body>
</html>

<%@ Page Language="VB" %>
<%@ outputcache duration="30" varybyparam="none" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="Server">
    Sub Page_Load()
        ' Create a Cache Dependency 
        ' using a CacheDependency object.
        Dim authorsDependency("authors.xml") As CacheDependency

        ' Make the page invalid if either of the
        ' cached items change or expire.        
        Response.AddCacheDependency(authorsDependency)

        ' Display the current time for cache reference
        lblOutputCacheMsg.Text = DateTime.Now.ToString()
        
        
    End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>Cache Dependencies</title> 
</head>
<body>
    <form id="Form1" method="post" runat="server">
        <table>
            <tbody>
                <tr>
                    <td style="WIDTH: 118px">
                        The page was generated at:</td>
                    <td>
                        <asp:Label id="lblOutputCacheMsg" runat="server"></asp:Label>
                    </td>
                </tr>
            </tbody>
        </table>
    </form>
</body>
</html>

Remarks

The AddCacheDependency method allows dependencies to be created between cached responses and a CacheDependency object.

Applies to