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HttpCachePolicy.AddValidationCallback Method

Registers a validation callback for the current response.

Namespace:  System.Web
Assembly:  System.Web (in System.Web.dll)

member AddValidationCallback : 
        handler:HttpCacheValidateHandler * 
        data:Object -> unit

Parameters

handler
Type: System.Web.HttpCacheValidateHandler

The HttpCacheValidateHandler value.

data
Type: System.Object

The arbitrary user-supplied data that is passed back to the AddValidationCallback delegate.

ExceptionCondition
ArgumentNullException

The specified handler is a null reference (Nothing in Visual Basic).

The AddValidationCallback method provides a mechanism to check the response programmatically in the cache before the response is returned to the client by the output cache.

Before the response is served from the Web server cache, all registered handlers are queried to ensure resource validity. If any handler sets a flag indicating that the cached response is not valid, the entry is marked as not valid and expelled from the cache. In this case, as well as when any handler indicates that the cached response should be ignored for this request, the request is then handled as if it were a cache miss.

AddValidationCallback is introduced in the .NET Framework version 3.5. For more information, see .NET Framework Versions and Dependencies.

The following code example demonstrates how to add a delegate to validate a request based on query string values.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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