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Marks all the contents of the Web Part cache as outdated.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)

'Declaration
Public Sub PartCacheInvalidate
'Usage
Dim instance As WebPart

instance.PartCacheInvalidate()

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method, which passes no arguments, marks all of the contents of the Web Part cache as outdated. Call the PartCacheInvalidate(Storage) method to mark all content of the specified storage type in the Web Part cache as outdated.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String) method to mark only the specified cached value of the specified storage type in the Web Part cache as outdated.

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") + "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;"))
         Me.RenderChildren(output)
      End Sub

      Private Function fetchData() As String
         Return DateTime.Now.ToLongTimeString()
      End Function
   End Class
End Namespace

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