VirtualDirectory Class
Definition
Important
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Represents a directory object in a virtual file or resource space.
public ref class VirtualDirectory abstract : System::Web::Hosting::VirtualFileBasepublic abstract class VirtualDirectory : System.Web.Hosting.VirtualFileBasetype VirtualDirectory = class
inherit VirtualFileBasePublic MustInherit Class VirtualDirectory
Inherits VirtualFileBase- Inheritance
Examples
The following code example is a VirtualDirectory class implementation that returns virtual directory information stored in a DataSet object. This code works with the code examples for the VirtualPathProvider and VirtualFile classes to provide virtual resources from a data store that is loaded into a DataSet object. For the complete instructions for compiling and running the example, see the Example section of the VirtualPathProvider class overview.
This example has two parts, the VirtualDirectory class implementation and the XML data file used to populate the DataSet object.
The first code example is an implementation of the VirtualDirectory class. In the constructor it uses a method on a custom VirtualPathProvider object to return a DataSet object. It then searches the DataSet object to retrieve the directory information associated with the virtual path provided.
using System;
using System.Collections;
using System.Data;
using System.Security.Permissions;
using System.Web;
using System.Web.Hosting;
namespace Samples.AspNet.CS
{
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermission(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal)]
public class SampleVirtualDirectory : VirtualDirectory
{
SamplePathProvider spp;
private bool exists;
public bool Exists
{
get { return exists; }
}
public SampleVirtualDirectory(string virtualDir, SamplePathProvider provider)
: base(virtualDir)
{
spp = provider;
GetData();
}
protected void GetData()
{
DataSet ds = spp.GetVirtualData();
// Clean up the path to match data in resource file.
string path = VirtualPath.Replace(HostingEnvironment.ApplicationVirtualPath, "");
path = path.TrimEnd('/');
// Get the virtual directory from the resource table.
DataTable dirs = ds.Tables["resource"];
DataRow[] rows = dirs.Select(
String.Format("(name = '{0}') AND (type='dir')", path));
// If the select returned a row, the directory exists.
if (rows.Length > 0)
{
exists = true;
// Get children from the resource table.
// This technique works for small numbers of virtual resources.
// Sites with moderate to large numbers of virtual
// resources should choose a method that consumes fewer
// computer resources.
DataRow[] childRows = dirs.Select(
String.Format("parentPath = '{0}'", path));
foreach (DataRow childRow in childRows)
{
string childPath = (string)childRow["path"];
if (childRow["type"].ToString() == "dir")
{
SampleVirtualDirectory svd = new SampleVirtualDirectory(childPath, spp);
children.Add(svd);
directories.Add(svd);
}
else
{
SampleVirtualFile svf = new SampleVirtualFile(childPath, spp);
children.Add(svf);
files.Add(svf);
}
}
}
}
private ArrayList children = new ArrayList();
public override IEnumerable Children
{
get { return children; }
}
private ArrayList directories = new ArrayList();
public override IEnumerable Directories
{
get { return directories; }
}
private ArrayList files = new ArrayList();
public override IEnumerable Files
{
get { return files; }
}
}
}
Imports System.Data
Imports System.Collections
Imports System.Security.Permissions
Imports System.Web
Imports System.Web.Hosting
Namespace Samples.AspNet.VB
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal), _
AspNetHostingPermission(SecurityAction.InheritanceDemand, level:=AspNetHostingPermissionLevel.Minimal)> _
Public Class SampleVirtualDirectory
Inherits VirtualDirectory
Private spp As SamplePathProvider
' Declare the variable the property uses.
Private existsValue As Boolean
Public ReadOnly Property exists() As Boolean
Get
Return existsValue
End Get
End Property
Public Sub New(ByVal virtualDir As String, ByVal provider As SamplePathProvider)
MyBase.New(virtualDir)
spp = provider
GetData()
End Sub
Protected Sub GetData()
' Get the data from the SamplePathProvider.
Dim spp As SamplePathProvider
spp = CType(HostingEnvironment.VirtualPathProvider, SamplePathProvider)
Dim ds As DataSet
ds = spp.GetVirtualData
' Clean up the path to match data in resource file.
Dim path As String
path = VirtualPath.Replace(HostingEnvironment.ApplicationVirtualPath, "")
Dim trimChars() As Char = {"/"c}
path = path.TrimEnd(trimChars)
' Get the virtual directory from the resource table.
Dim dirs As DataTable
dirs = ds.Tables("resource")
Dim rows As DataRow()
rows = dirs.Select( _
String.Format("(name = '{0}') AND (type='dir')", path))
' If the select returned a row, the directory exits.
If (rows.Length > 0) Then
existsValue = True
' Get the children from the resource table.
' This technique works for small numbers of virtual resources.
' Sites with moderate to large numbers of virtual
' resources should choose a method that consumes fewer
' computer resources.
Dim childRows As DataRow()
childRows = dirs.Select( _
String.Format("parentPath = '{0}'", path))
For Each childRow As DataRow In childRows
Dim childPath As String
childPath = CType(childRow("path"), String)
If (childRow("type").ToString = "dir") Then
Dim svd As New SampleVirtualDirectory(childPath, spp)
childrenValue.Add(svd)
directoriesValue.Add(svd)
Else
Dim svf As New SampleVirtualFile(childPath, spp)
childrenValue.Add(svf)
directoriesValue.Add(svf)
End If
Next
End If
End Sub
Private childrenValue As ArrayList
Public Overrides ReadOnly Property Children() As System.Collections.IEnumerable
Get
Return childrenValue
End Get
End Property
Private directoriesValue As ArrayList
Public Overrides ReadOnly Property Directories() As System.Collections.IEnumerable
Get
Return directoriesValue
End Get
End Property
Private filesValue As ArrayList
Public Overrides ReadOnly Property Files() As System.Collections.IEnumerable
Get
Return filesValue
End Get
End Property
End Class
End Namespace
The second example is the XML data file used to populate the DataSet object returned by the custom VirtualPathProvider object. This XML data is used to demonstrate using the VirtualPathProvider, VirtualFile, and VirtualDirectory classes to retrieve data from external data, and is not intended to represent a production-quality data store.
<?xml version="1.0" encoding="utf-8" ?>
<resource type="dir"
path="/vrDir"
parentPath=""
content="">
<resource type="file"
path="/vrDir/Level1FileA.vrf"
parentPath="/vrDir"
content="This is the content of file Level1FileA." >
</resource>
<resource type="file"
path="/vrDir/Level1FileB.vrf"
parentPath="/vrDir"
content="This is the content of file Level1FileB.">
</resource>
<resource type="dir"
path="/vrDir/Level2DirA"
parentPath="/vrDir"
content="">
<resource type="file"
path="/vrDir/Level2DirA/Level2FileA.vrf"
parentPath="/vrDir/Level2DirA"
content="This is the content of file Level2FileA." >
</resource>
<resource type="file"
path="/vrDir/Level2DirA/Level2FileB.vrf"
parentPath="/vrDir/Level2DirA"
content="This is the content of file Level2FileB.">
</resource>
</resource>
<resource type="dir"
path="/vrDir/Level2DirB"
parentPath="/vrDir"
content="">
<resource type="file"
path="/vrDir/Level2DirB/Level2FileA.vrf"
parentPath="/vrDir/Level2DirB"
content="This is the content of file Level2FileA." >
</resource>
<resource type="file"
path="/vrDir/Level2DirB/Level2FileB.vrf"
parentPath="/vrDir/Level2DirB"
content="This is the content of file Level2FileB.">
</resource>
</resource>
</resource>
Remarks
The VirtualDirectory class is the base class for objects that represent directories in a virtual file system. Typically, you would implement a descendent of the VirtualDirectory class for each VirtualPathProvider class descendent in your Web application.
Notes to Implementers
When you inherit from the VirtualDirectory class, you must override the Children, Directories, and Files properties to return an object implementing the IEnumerable interface.
If your virtual-directory structure contains moderate to large numbers of virtual resources, you should take care to minimize the system resources consumed when enumerating the virtual directory by calling the Children, Directories, or Files properties.
Constructors
| VirtualDirectory(String) |
Initializes a new instance of the VirtualDirectory class. |
Properties
| Children |
Gets a list of the files and subdirectories contained in this virtual directory. |
| Directories |
Gets a list of all the subdirectories contained in this directory. |
| Files |
Gets a list of all files contained in this directory. |
| IsDirectory |
Gets a value that indicates that this is a virtual resource that should be treated as a directory. |
| Name |
Gets the display name of the virtual resource. (Inherited from VirtualFileBase) |
| VirtualPath |
Gets the virtual file path. (Inherited from VirtualFileBase) |
Methods
| CreateObjRef(Type) |
Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject) |
| Equals(Object) |
Determines whether the specified object is equal to the current object. (Inherited from Object) |
| GetHashCode() |
Serves as the default hash function. (Inherited from Object) |
| GetLifetimeService() |
Obsolete.
Retrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject) |
| GetType() |
Gets the Type of the current instance. (Inherited from Object) |
| InitializeLifetimeService() |
Gives a VirtualFileBase instance an infinite lifetime by preventing a lease from being created. (Inherited from VirtualFileBase) |
| MemberwiseClone() |
Creates a shallow copy of the current Object. (Inherited from Object) |
| MemberwiseClone(Boolean) |
Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject) |
| ToString() |
Returns a string that represents the current object. (Inherited from Object) |
