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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)

Public Overridable Function GetCacheDependency ( _
	virtualPath As String, _
	virtualPathDependencies As IEnumerable, _
	utcStart As DateTime _
) As CacheDependency
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)


Type: System.String

The path to the primary virtual resource.

Type: System.Collections.IEnumerable

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

Type: System.DateTime

The UTC time at which the virtual resources were read.

Return Value

Type: System.Web.Caching.CacheDependency
A CacheDependency object for the specified virtual resources.

The default implementation of the GetCacheDependency method returns Nothing. 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


    If fullPathDependencies Is Nothing Then 
      Return Nothing 
    End If 

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

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

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.

.NET Framework

Supported in: 3.5, 3.0, 2.0