HttpCacheValidateHandler Delegate
Represents a method that is called to validate a cached item before the item is served from the cache.
Assembly: System.Web (in System.Web.dll)
'Declaration Public Delegate Sub HttpCacheValidateHandler ( _ context As HttpContext, _ data As Object, _ ByRef validationStatus As HttpValidationStatus _ ) 'Usage Dim instance As New HttpCacheValidateHandler(AddressOf HandlerMethod)
Parameters
- context
- Type: System.Web.HttpContext
The HttpContext object containing information about the current request.
- data
- Type: System.Object
User-supplied data used to validate the cached item.
- validationStatus
- Type: System.Web.HttpValidationStatus%
An HttpValidationStatus enumeration value. Your delegate should set this value to indicate the result of the validation.
If a cached item is invalidated within the scope of the HttpCacheValidateHandler method, it is evicted from the cache and the request for the item is treated as a cache miss.
| Topic | Location |
|---|---|
| How to: Check the Validity of a Cached Page | Building ASP .NET Web Applications |
| How to: Check the Validity of a Cached Page | Building ASP .NET Web Applications |
The following code example demonstrates how to add a new cache validation delegate to an application.
Private Sub Page_Load(sender As Object, e As EventArgs) Response.Cache.AddValidationCallback(New HttpCacheValidateHandler(AddressOf CacheValidate1), Nothing) End Sub Public Sub CacheValidate1(context As HttpContext, data As Object, ByRef status As HttpValidationStatus) If context.Request.QueryString("Valid") = "false" Then status = HttpValidationStatus.Invalid Else status = HttpValidationStatus.Valid End If End Sub
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.