IHierarchyData Interface

 
System_CAPS_noteNote

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Exposes a node of a hierarchical data structure, including the node object and some properties that describe characteristics of the node. Objects that implement the IHierarchyData interface can be contained in IHierarchicalEnumerable collections, and are used by ASP.NET site navigation and data source controls.

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

Public Interface IHierarchyData

NameDescription
System_CAPS_pubpropertyHasChildren

Indicates whether the hierarchical data node that the IHierarchyData object represents has any child nodes.

System_CAPS_pubpropertyItem

Gets the hierarchical data node that the IHierarchyData object represents.

System_CAPS_pubpropertyPath

Gets the hierarchical path of the node.

System_CAPS_pubpropertyType

Gets the name of the type of Object contained in the Item property.

NameDescription
System_CAPS_pubmethodGetChildren()

Gets an enumeration object that represents all the child nodes of the current hierarchical node.

System_CAPS_pubmethodGetParent()

Gets an IHierarchyData object that represents the parent node of the current hierarchical node.

The IHierarchyData interface is implemented by classes that represent nodes of a hierarchical structure, and track the hierarchical relationships to their parent and child nodes. Classes that implement the IHierarchyData interface can be contained in collections that implement the IHierarchicalEnumerable interface.

The following code example demonstrates how to implement the IHierarchyData interface with a class that wraps a FileSystemInfo object. The FileSystemInfo class is a good example of a hierarchical data node, which the IHierarchyData interface represents for ASP.NET hierarchical data source controls. This code example is part of a larger example provided for the HierarchicalDataSourceControl class.


Public Class FileSystemHierarchyData
    Implements IHierarchyData

    Public Sub New(ByVal obj As FileSystemInfo)
        fileSystemObject = obj
    End Sub

    Private fileSystemObject As FileSystemInfo = Nothing

    Public Overrides Function ToString() As String
        Return fileSystemObject.Name
    End Function

    ' IHierarchyData implementation.
    Public Overridable ReadOnly Property HasChildren() As Boolean _
     Implements IHierarchyData.HasChildren
        Get
            If GetType(DirectoryInfo) Is fileSystemObject.GetType() Then
                Dim temp As DirectoryInfo = _
                    CType(fileSystemObject, DirectoryInfo)
                Return temp.GetFileSystemInfos().Length > 0
            Else
                Return False
            End If
        End Get
    End Property
    ' DirectoryInfo returns the OriginalPath, while FileInfo returns
    ' a fully qualified path.

    Public Overridable ReadOnly Property Path() As String _
     Implements IHierarchyData.Path
        Get
            Return fileSystemObject.ToString()
        End Get
    End Property

    Public Overridable ReadOnly Property Item() As Object _
     Implements IHierarchyData.Item
        Get
            Return fileSystemObject
        End Get
    End Property

    Public Overridable ReadOnly Property Type() As String _
     Implements IHierarchyData.Type
        Get
            Return "FileSystemData"
        End Get
    End Property

    Public Overridable Function GetChildren() _
        As IHierarchicalEnumerable _
        Implements IHierarchyData.GetChildren

        Dim children As New FileSystemHierarchicalEnumerable()

        If GetType(DirectoryInfo) Is fileSystemObject.GetType() Then
            Dim temp As DirectoryInfo = _
                CType(fileSystemObject, DirectoryInfo)
            Dim fsi As FileSystemInfo
            For Each fsi In temp.GetFileSystemInfos()
                children.Add(New FileSystemHierarchyData(fsi))
            Next fsi
        End If
        Return children
    End Function 'GetChildren


    Public Overridable Function GetParent() As IHierarchyData _
     Implements IHierarchyData.GetParent
        Dim parentContainer As New FileSystemHierarchicalEnumerable()

        If GetType(DirectoryInfo) Is fileSystemObject.GetType() Then
            Dim temp As DirectoryInfo = _
                CType(fileSystemObject, DirectoryInfo)
            Return New FileSystemHierarchyData(temp.Parent)
        ElseIf GetType(FileInfo) Is fileSystemObject.GetType() Then
            Dim temp As FileInfo = CType(fileSystemObject, FileInfo)
            Return New FileSystemHierarchyData(temp.Directory)
        End If
        ' If FileSystemObj is any other kind of FileSystemInfo, ignore it.
        Return Nothing
    End Function 'GetParent
End Class 'FileSystemHierarchyData

The following code example demonstrates how to recursively iterate through an IHierarchicalEnumerable collection, extract the IHierarchyData item from the enumerator using the GetHierarchyData method, and perform basic work with the data item.

<%@ Page Language="VB" AutoEventWireup="true" CodeFile="ihd_1.aspx.vb" Inherits="ihd_1_aspx" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

    </div>
    </form>
</body>
</html>

.NET Framework
Available since 2.0
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