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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

Parameters

virtualPath
Type: System.String
The path to the primary virtual resource.
virtualPathDependencies
Type: System.Collections.IEnumerable
An array of paths to other resources required by the primary virtual resource.
utcStart
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

      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


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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