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VirtualPathProvider.GetCacheDependency Method

Creates a cache dependency based on the specified virtual paths.

Namespace: System.Web.Hosting
Assembly: System.Web (in system.web.dll)

'Declaration
Public Overridable Function GetCacheDependency ( _
	virtualPath As String, _
	virtualPathDependencies As IEnumerable, _
	utcStart As DateTime _
) As CacheDependency
'Usage
Dim instance As VirtualPathProvider
Dim virtualPath As String
Dim virtualPathDependencies As IEnumerable
Dim utcStart As DateTime
Dim returnValue As CacheDependency

returnValue = instance.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart)
public CacheDependency GetCacheDependency (
	String virtualPath, 
	IEnumerable virtualPathDependencies, 
	DateTime utcStart
)
public function GetCacheDependency (
	virtualPath : String, 
	virtualPathDependencies : IEnumerable, 
	utcStart : DateTime
) : CacheDependency
Not applicable.

Parameters

virtualPath

The path to the primary virtual resource.

virtualPathDependencies

An array of paths to other resources required by the primary virtual resource.

utcStart

The UTC time at which the virtual resources were read.

Return Value

A CacheDependency object for the specified virtual resources.

The default implementation of the GetCacheDependency method returns a null reference (Nothing in Visual Basic). To cache virtual resources for later use you must override either the GetCacheDependency method or the GetFileHash method.

The following code example implements the GetCacheDependency method for a custom VirtualPathProvider class. For the full code required to run the example, see the Example section of the VirtualPathProvider class overview topic.

Public Overrides Function GetCacheDependency(ByVal virtualPath As String, ByVal virtualPathDependencies As IEnumerable, ByVal utcStart As Date) As CacheDependency
  If (IsPathVirtual(virtualPath)) Then

    Dim fullPathDependencies As System.Collections.Specialized.StringCollection
    fullPathDependencies = Nothing

    ' Get the full path to all dependencies.
    For Each virtualDependency As String In virtualPathDependencies
      If fullPathDependencies Is Nothing Then
        fullPathDependencies = New System.Collections.Specialized.StringCollection
      End If

      fullPathDependencies.Add(virtualDependency)
    Next

    If fullPathDependencies Is Nothing Then
      Return Nothing
    End If

    Dim fullPathDependenciesArray As String()
    fullPathDependencies.CopyTo(fullPathDependenciesArray, 0)

    Return New CacheDependency(fullPathDependenciesArray, utcStart)
  Else
    Return Previous.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart)
  End If
End Function

Windows 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0
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