WebPart.PartCacheInvalidate method
Marks all the contents of the Web Part cache as outdated.
Namespace: Microsoft.SharePoint.WebPartPages
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Syntax
'Declaration
Public Sub PartCacheInvalidate
'Usage
Dim instance As WebPart
instance.PartCacheInvalidate()
public void PartCacheInvalidate()
Remarks
Calling the [M:Microsoft.SharePoint.WebPartPages.WebPart.PartCacheInvalidate()] method, which passes no arguments, marks all of the contents of the Web Part cache as outdated. Call the PartCacheInvalidate(Storage) method to mark all content of the specified storage type in the Web Part cache as outdated. Call the PartCacheInvalidate(Storage, String) method to mark only the specified cached value of the specified storage type in the Web Part cache as outdated.
Examples
The following code example shows a Web Part that caches and displays the time when it is first rendered, and provides a button to refresh the Web Part cache with the current time.
Imports System
Imports System.ComponentModel
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Xml.Serialization
Imports Microsoft.SharePoint
Imports Microsoft.SharePoint.Utilities
Imports Microsoft.SharePoint.WebPartPages
Namespace WebPartLibrary1
<DefaultProperty("Text"), _
ToolboxData("<{0}:CacheSample runat=server></{0}:CacheSample>"), _
XmlRoot([Namespace] := "WebPartLibrary1")> _
Public Class CacheSample
Inherits Microsoft.SharePoint.WebPartPages.WebPart
Private refreshButton As Button
Public Sub New()
AddHandler Me.PreRender, AddressOf UpdateCache
End Sub
Protected Overrides Sub CreateChildControls()
refreshButton = New Button()
refreshButton.Text = "Refresh Cache"
AddHandler refreshButton.Click, AddressOf refreshButton_click
Me.Controls.Add(refreshButton)
End Sub
Public Sub UpdateCache(o As Object, e As System.EventArgs)
If Me.PartCacheRead(Storage.Shared, "cacheKey") Is Nothing Then
Me.PartCacheWrite(Storage.Shared, "cacheKey", fetchData(), TimeSpan.FromSeconds(10))
End If
End Sub
Private Sub refreshButton_click(o As Object, e As System.EventArgs)
Me.PartCacheInvalidate(Storage.Shared, "cacheKey")
End Sub
Protected Overrides Sub RenderWebPart(output As HtmlTextWriter)
output.Write("Cache Value: ")
output.Write((PartCacheRead(Storage.Shared, "cacheKey") + " "))
Me.RenderChildren(output)
End Sub
Private Function fetchData() As String
Return DateTime.Now.ToLongTimeString()
End Function
End Class
End Namespace
using System;
using System.ComponentModel;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml.Serialization;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Utilities;
using Microsoft.SharePoint.WebPartPages;
namespace WebPartLibrary1
{
/// <summary>
/// Summary description for CacheSample.
/// </summary>
[DefaultProperty("Text"),
ToolboxData("<{0}:CacheSample runat=server></{0}:CacheSample>"),
XmlRoot(Namespace="WebPartLibrary1")]
public class CacheSample : Microsoft.SharePoint.WebPartPages.WebPart
{
Button refreshButton;
public CacheSample()
{
this.PreRender+=new EventHandler(UpdateCache);
}
protected override void CreateChildControls()
{
refreshButton = new Button();
refreshButton.Text="Refresh Cache";
refreshButton.Click+=new EventHandler(refreshButton_click);
this.Controls.Add(refreshButton);
}
public void UpdateCache(object o, System.EventArgs e)
{
if(this.PartCacheRead(Storage.Shared,"cacheKey") == null)
{
this.PartCacheWrite(Storage.Shared,"cacheKey", fetchData(), TimeSpan.FromSeconds(10));
}
}
private void refreshButton_click(object o, System.EventArgs e)
{
this.PartCacheInvalidate(Storage.Shared, "cacheKey");
}
protected override void RenderWebPart(HtmlTextWriter output)
{
output.Write("Cache Value: ");
output.Write(PartCacheRead(Storage.Shared,"cacheKey")+ " ");
this.RenderChildren(output);
}
private string fetchData()
{
return DateTime.Now.ToLongTimeString();
}
}
}