ControlCachePolicy.SetExpires(DateTime) Method

Reference

Definition

Namespace:: System.Web.UI

Assembly:: System.Web.dll

Important

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Instructs the BasePartialCachingControl control that wraps the user control to expire the cache entry at the specified date and time.

public:
 void SetExpires(DateTime expirationTime);

public void SetExpires (DateTime expirationTime);

member this.SetExpires : DateTime -> unit

Public Sub SetExpires (expirationTime As DateTime)

Parameters

expirationTime: DateTime

A DateTime after which the cached entry expires.

Exceptions

HttpException

The user control is not associated with a BasePartialCachingControl and is not cacheable.

Examples

The following code example demonstrates how a user control can be loaded dynamically and manipulated programmatically at run time. The PartialCachingAttribute attribute is applied to a user control named SimpleControl, which means the user control is wrapped by a PartialCachingControl control at run time. The SimpleControl object's caching settings can be programmatically manipulated through its associated ControlCachePolicy object, which is available through a reference to the PartialCachingControl control that wraps it. In this example, the Duration property is examined during page initialization and changed using the SetSlidingExpiration and SetExpires methods if some conditions are met. This example is part of a larger example provided for the ControlCachePolicy class.

<%@ Page Language="C#" %>
<%@ Reference Control="SimpleControl.ascx" %>
<script language="C#" runat="server">

// The following example demonstrates how to load a user control dynamically at run time, and
// work with the ControlCachePolicy object associated with it.

// Loads and displays a UserControl defined in a seperate Logonform.ascx file.
// You need to have "SimpleControl.ascx" file in 
// the same directory as the aspx file. 

void Page_Init(object sender, System.EventArgs e) {
    
    // Obtain a PartialCachingControl object which wraps the 'LogOnControl' user control.
    PartialCachingControl pcc = LoadControl("SimpleControl.ascx") as PartialCachingControl;        
    
    // If the control is slated to expire in greater than 60 Seconds
    if (pcc.CachePolicy.Duration > TimeSpan.FromSeconds(60) ) 
    {        
        // Make it expire faster. Set a new expiration time to 30 seconds, and make it
        // an absolute expiration if it isnt already.        
        pcc.CachePolicy.SetExpires(DateTime.Now.Add(TimeSpan.FromSeconds(30)));
        pcc.CachePolicy.SetSlidingExpiration(false);
    }                    
    Controls.Add(pcc);
}
</script>

<%@ Page Language="VB" %>
<%@ Reference Control="SimpleControl.ascx" %>
<script language="VB" runat="server">

    ' The following example demonstrates how to load a user control dynamically at run time, and
    ' work with the ControlCachePolicy object associated with it.

    ' Loads and displays a UserControl defined in a seperate Logonform.ascx file.
    ' You need to have "SimpleControl.ascx" file in 
    ' the same directory as the aspx file. 

    Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs)
    
        ' Obtain a PartialCachingControl object which wraps the 'LogOnControl' user control.
        Dim pcc As PartialCachingControl
        pcc = LoadControl("SimpleControl.ascx")
    
        ' If the control is slated to expire in greater than 60 Seconds
        If (pcc.CachePolicy.Duration > TimeSpan.FromSeconds(60)) Then
            ' Make it expire faster. Set a new expiration time to 30 seconds, and make it
            ' an absolute expiration if it isnt already.        
            pcc.CachePolicy.SetExpires(DateTime.Now.Add(TimeSpan.FromSeconds(30)))
            pcc.CachePolicy.SetSlidingExpiration(False)
        End If
        Controls.Add(pcc)
    End Sub
</script>

Remarks

Use the SetExpires and SetSlidingExpiration methods (passing true) to instruct the BasePartialCachingControl control that wraps the user control to use a sliding expiration caching policy instead of an absolute expiration policy. Use the SetExpires method and the SetSlidingExpiration method (passing false) to specify an absolute expiration policy.

Applies to

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