VB.Net Tutorial/XML/XML Tree

Load XML document to a TreeView

"Visual Basic.NET How to Program, Second Edition
"by Harvey M. Deitel (Author), Paul J. Deitel (Author), Tem R. Nieto (Author)
" Publisher: Prentice Hall; 2 edition (December 11, 2001)
" Language: English
" ISBN-10: 0130293636
" ISBN-13: 978-0130293633

Imports System.Xml
Imports System.Windows.Forms
Imports System.CodeDom.rupiler " contains TempFileCollection

public class LoadXMLTreeView
   public Shared Sub Main
        Application.Run(New FrmXmlDom)
   End Sub
End class
Public Class FrmXmlDom
   Inherits Form
   " TextBox and TreeView for displaying data
   Friend WithEvents txtConsole As TextBox
   Friend WithEvents treXml As TreeView
   " Buttons for building, printing and reseting DOM tree
   Friend WithEvents cmdBuild As Button
   Friend WithEvents cmdPrint As Button
   Friend WithEvents cmdReset As Button
   Private source As XmlDocument " reference to "XML document"
   " reference copy of source"s "XML document"
   Private copy As XmlDocument
   Private tree As TreeNode " TreeNode reference
   Public Sub New()
      MyBase.New()
      " This call is required by the Windows Form Designer.
      InitializeComponent()
      " Add any initialization after the 
      " InitializeComponent() call
      " create XmlDocument and load letter.xml
      source = New XmlDocument()
      source.Load("YourFile.xml")
      " initialize references to Nothing
      copy = Nothing
      tree = Nothing
   End Sub " New
#Region " Windows Form Designer generated code "
   "Form overrides dispose to clean up the component list.
   Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
      If disposing Then
         If Not (components Is Nothing) Then
            components.Dispose()
         End If
      End If
      MyBase.Dispose(disposing)
   End Sub
   "Required by the Windows Form Designer
   Private components As System.ruponentModel.Container
   "NOTE: The following procedure is required by the Windows Form Designer
   "It can be modified using the Windows Form Designer.  
   "Do not modify it using the code editor.
   <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
      Me.treXml = New System.Windows.Forms.TreeView()
      Me.cmdBuild = New System.Windows.Forms.Button()
      Me.txtConsole = New System.Windows.Forms.TextBox()
      Me.cmdPrint = New System.Windows.Forms.Button()
      Me.cmdReset = New System.Windows.Forms.Button()
      Me.SuspendLayout()
      "
      "treXml
      "
      Me.treXml.ImageIndex = -1
      Me.treXml.Location = New System.Drawing.Point(8, 40)
      Me.treXml.Name = "treXml"
      Me.treXml.SelectedImageIndex = -1
      Me.treXml.Size = New System.Drawing.Size(344, 192)
      Me.treXml.TabIndex = 3
      "
      "cmdBuild
      "
      Me.cmdBuild.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
      Me.cmdBuild.Location = New System.Drawing.Point(8, 8)
      Me.cmdBuild.Name = "cmdBuild"
      Me.cmdBuild.Size = New System.Drawing.Size(104, 23)
      Me.cmdBuild.TabIndex = 0
      Me.cmdBuild.Text = "Build"
      "
      "txtConsole
      "
      Me.txtConsole.Location = New System.Drawing.Point(8, 240)
      Me.txtConsole.Multiline = True
      Me.txtConsole.Name = "txtConsole"
      Me.txtConsole.ScrollBars = System.Windows.Forms.ScrollBars.Vertical
      Me.txtConsole.Size = New System.Drawing.Size(344, 96)
      Me.txtConsole.TabIndex = 4
      Me.txtConsole.Text = ""
      "
      "cmdPrint
      "
      Me.cmdPrint.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
      Me.cmdPrint.Location = New System.Drawing.Point(128, 8)
      Me.cmdPrint.Name = "cmdPrint"
      Me.cmdPrint.Size = New System.Drawing.Size(104, 23)
      Me.cmdPrint.TabIndex = 1
      Me.cmdPrint.Text = "Print"
      "
      "cmdReset
      "
      Me.cmdReset.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
      Me.cmdReset.Location = New System.Drawing.Point(248, 8)
      Me.cmdReset.Name = "cmdReset"
      Me.cmdReset.Size = New System.Drawing.Size(104, 23)
      Me.cmdReset.TabIndex = 2
      Me.cmdReset.Text = "Reset"
      "
      "FrmXmlDom
      "
      Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
      Me.ClientSize = New System.Drawing.Size(360, 341)
      Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.txtConsole, Me.treXml, Me.cmdReset, Me.cmdPrint, Me.cmdBuild})
      Me.Name = "FrmXmlDom"
      Me.Text = "Xml Dom"
      Me.ResumeLayout(False)
   End Sub
#End Region
   " event handler for cmdBuild click event
   Private Sub cmdBuild_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles cmdBuild.Click
      " determine if copy has been built already
      If Not copy Is Nothing Then
         Return " document already exists
      End If
      " instantiate XmlDocument and TreeNode
      copy = New XmlDocument()
      tree = New TreeNode()
      " add root node name to TreeNode and add
      " TreeNode to TreeView control
      tree.Text = source.Name " assigns #root
      treXml.Nodes.Add(tree)
      " build node and tree hierarchy
      BuildTree(source, copy, tree)
   End Sub " cmdBuild_Click
   " event handler for cmdPrint click event
   Private Sub cmdPrint_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles cmdPrint.Click
      " exit if copy does not reference an XmlDocument
      If copy Is Nothing Then
         Return
      End If
      " create temporary XML file
      Dim file As TempFileCollection = New TempFileCollection()
      " create file that is deleted at program termination
      file.AddExtension("xml", False)
      Dim filename As String() = New String(0) {}
      file.CopyTo(filename, 0)
      " write XML data to disk
      Dim writer As XmlTextWriter = _
        New XmlTextWriter(filename(0), _
        System.Text.Encoding.UTF8)
      copy.WriteTo(writer)
      writer.Close()
      " parse and load temporary XML document
      Dim reader As XmlTextReader = _
         New XmlTextReader(filename(0))
      " read, format and display data
      While reader.Read
         If reader.NodeType = XmlNodeType.EndElement Then
            txtConsole.Text &= "/"
         End If
         If reader.Name <> String.Empty Then
            txtConsole.Text &= reader.Name & vbCrLf
         End If
         If reader.Value <> String.Empty Then
            txtConsole.Text &= vbTab & reader.Value & vbCrLf
         End If
      End While
      reader.Close()
   End Sub " cmdPrint_Click
   " handle cmdReset click event
   Private Sub cmdReset_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles cmdReset.Click
      " remove TreeView nodes
      If Not tree Is Nothing Then
         treXml.Nodes.Remove(tree)
      End If
      treXml.Refresh() " force TreeView update
      " delete XmlDocument and tree
      copy = Nothing
      tree = Nothing
      txtConsole.Clear() " clear text box
   End Sub " cmdReset_Click
   " construct DOM tree
   Private Sub BuildTree(ByVal xmlSourceNode As XmlNode, _
      ByVal documentValue As XmlNode, _
      ByVal treeNode As TreeNode)
      " create XmlNodeReader to access XML document
      Dim nodeReader As XmlNodeReader = _
         New XmlNodeReader(xmlSourceNode)
      " represents current node in DOM tree
      Dim currentNode As XmlNode = Nothing
      " treeNode to add to existing tree
      Dim newNode As TreeNode = New TreeNode()
      " references modified node type for CreateNode
      Dim modifiedNodeType As XmlNodeType
      While nodeReader.Read
         " get current node type
         modifiedNodeType = nodeReader.NodeType
         " check for EndElement, store as Element
         If modifiedNodeType = XmlNodeType.EndElement Then
            modifiedNodeType = XmlNodeType.Element
         End If
         " create node copy
         currentNode = copy.CreateNode(modifiedNodeType, _
            nodeReader.Name, nodeReader.NamespaceURI)
         " build tree based on node type
         Select Case nodeReader.NodeType
            " if Text node, add its value to tree
         Case XmlNodeType.Text
               newNode.Text = nodeReader.Value
               treeNode.Nodes.Add(newNode)
               " append Text node value to currentNode data
               CType(currentNode, XmlText).AppendData _
                  (nodeReader.Value)
               documentValue.AppendChild(currentNode)
               " if EndElement, move up tree
            Case XmlNodeType.EndElement
               documentValue = documentValue.ParentNode
               treeNode = treeNode.Parent
               " if new element, add name and traverse tree
            Case XmlNodeType.Element
               " determine if element contains content
               If Not nodeReader.IsEmptyElement Then
                  " assign node text, add newNode as child
                  newNode.Text = nodeReader.Name
                  treeNode.Nodes.Add(newNode)
                  " set treeNode to last child
                  treeNode = newNode
                  documentValue.AppendChild(currentNode)
                  documentValue = documentValue.LastChild
               Else " do not traverse empty elements
                  " assign NodeType string to newNode
                  newNode.Text = nodeReader.NodeType.ToString
                  treeNode.Nodes.Add(newNode)
                  documentValue.AppendChild(currentNode)
               End If
            Case Else " all other types, display node type
               newNode.Text = nodeReader.NodeType.ToString
               treeNode.Nodes.Add(newNode)
               documentValue.AppendChild(currentNode)
         End Select
         newNode = New TreeNode()
      End While
      " update TreeView control
      treXml.ExpandAll()
      treXml.Refresh()
   End Sub " BuildTree
End Class " FrmXmlDom
" *************************************************************
" * (C) Copyright 2002 by Deitel & Associates, Inc.           *
" *     and Prentice Hall.                                    *
" * All Rights Reserved.                                      *
" *                                                           *
" * DISCLAIMER: The authors and publisher of this book have   *
" * used their best efforts in preparing the book. These      *
" * efforts include the development, research, and testing of *
" * the theories and programs to determine their              *
" * effectiveness. The authors and publisher make no warranty *
" * of any kind, expressed or implied, with regard to these   *
" * programs or to the documentation contained in these books.*
" * The authors and publisher shall not be liable in any event*
" * for incidental or consequential damages in connection     *
" * with, or arising out of, the furnishing, performance, or  *
" * use of these programs.                                    *
" *************************************************************

XML path navigator

"Visual Basic.NET How to Program, Second Edition
"by Harvey M. Deitel (Author), Paul J. Deitel (Author), Tem R. Nieto (Author)
" Publisher: Prentice Hall; 2 edition (December 11, 2001)
" Language: English
" ISBN-10: 0130293636
" ISBN-13: 978-0130293633

Imports System.Windows.Forms
Imports System.Xml.XPath 
public class FrmPathNavigatorDemo
   public Shared Sub Main
        Application.Run(New FrmPathNavigator)
   End Sub
End class
Public Class FrmPathNavigator
   Inherits Form
   " GroupBox contains Controls for locating XML file
   Friend WithEvents locateGroupBox As GroupBox
   Friend WithEvents cmdSelect As Button
   Friend WithEvents cboSelect As ComboBox
   Friend WithEvents txtSelect As TextBox
   " GroupBox contains Controls for navigating DOM tree
   Friend WithEvents navigateGroupBox As GroupBox
   Friend WithEvents cmdNext As Button
   Friend WithEvents cmdPrevious As Button
   Friend WithEvents cmdParent As Button
   Friend WithEvents cmdFirstChild As Button
   " TreeView displays DOM-tree results
   Friend WithEvents trePath As TreeView
   " navigator to traverse document
   Private xPath As XPathNavigator
   " references document for use by XPathNavigator
   Private document As XPathDocument
   " references TreeNode list used by TreeView control
   Private tree As TreeNode
   Public Sub New()
      MyBase.New()
      " This call is required by the Windows Form Designer.
      InitializeComponent()
      " Add any initialization after the 
      " InitializeComponent() call
      " load in XML document
      document = New XPathDocument("YourFile.xml")
      " create nagivator
      xPath = document.CreateNavigator
      " create root node for TreeNodes
      tree = New TreeNode()
      tree.Text = xPath.NodeType.ToString " #root
      trePath.Nodes.Add(tree)             " add tree
      " update TreeView control
      trePath.ExpandAll()
      trePath.Refresh()
      trePath.SelectedNode = tree         " highlight root
   End Sub " New
#Region " Windows Form Designer generated code "
   "Form overrides dispose to clean up the component list.
   Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
      If disposing Then
         If Not (components Is Nothing) Then
            components.Dispose()
         End If
      End If
      MyBase.Dispose(disposing)
   End Sub
   "Required by the Windows Form Designer
   Private components As System.ruponentModel.Container
   "NOTE: The following procedure is required by the Windows Form Designer
   "It can be modified using the Windows Form Designer.  
   "Do not modify it using the code editor.
   <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
      Me.cboSelect = New System.Windows.Forms.ruboBox()
      Me.trePath = New System.Windows.Forms.TreeView()
      Me.navigateGroupBox = New System.Windows.Forms.GroupBox()
      Me.cmdFirstChild = New System.Windows.Forms.Button()
      Me.cmdParent = New System.Windows.Forms.Button()
      Me.cmdNext = New System.Windows.Forms.Button()
      Me.cmdPrevious = New System.Windows.Forms.Button()
      Me.txtSelect = New System.Windows.Forms.TextBox()
      Me.locateGroupBox = New System.Windows.Forms.GroupBox()
      Me.cmdSelect = New System.Windows.Forms.Button()
      Me.navigateGroupBox.SuspendLayout()
      Me.locateGroupBox.SuspendLayout()
      Me.SuspendLayout()
      "
      "cboSelect
      "
      Me.cboSelect.DropDownWidth = 121
      Me.cboSelect.Items.AddRange(New Object() {"/sports", "/sports/game/name", "/sports/game/paragraph", "/sports/game [name="Cricket"]"})
      Me.cboSelect.Location = New System.Drawing.Point(104, 32)
      Me.cboSelect.Name = "cboSelect"
      Me.cboSelect.Size = New System.Drawing.Size(224, 24)
      Me.cboSelect.TabIndex = 1
      "
      "trePath
      "
      Me.trePath.FullRowSelect = True
      Me.trePath.HideSelection = False
      Me.trePath.ImageIndex = -1
      Me.trePath.Location = New System.Drawing.Point(8, 272)
      Me.trePath.Name = "trePath"
      Me.trePath.SelectedImageIndex = -1
      Me.trePath.Size = New System.Drawing.Size(336, 136)
      Me.trePath.TabIndex = 2
      "
      "navigateGroupBox
      "
      Me.navigateGroupBox.Controls.AddRange(New System.Windows.Forms.Control() {Me.cmdFirstChild, Me.cmdParent, Me.cmdNext, Me.cmdPrevious})
      Me.navigateGroupBox.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
      Me.navigateGroupBox.Location = New System.Drawing.Point(84, 144)
      Me.navigateGroupBox.Name = "navigateGroupBox"
      Me.navigateGroupBox.Size = New System.Drawing.Size(184, 120)
      Me.navigateGroupBox.TabIndex = 1
      Me.navigateGroupBox.TabStop = False
      Me.navigateGroupBox.Text = "Navigation Controls"
      "
      "cmdFirstChild
      "
      Me.cmdFirstChild.Location = New System.Drawing.Point(104, 56)
      Me.cmdFirstChild.Name = "cmdFirstChild"
      Me.cmdFirstChild.TabIndex = 5
      Me.cmdFirstChild.Text = "First Child"
      "
      "cmdParent
      "
      Me.cmdParent.Location = New System.Drawing.Point(8, 56)
      Me.cmdParent.Name = "cmdParent"
      Me.cmdParent.TabIndex = 4
      Me.cmdParent.Text = "Parent"
      "
      "cmdNext
      "
      Me.cmdNext.Location = New System.Drawing.Point(56, 88)
      Me.cmdNext.Name = "cmdNext"
      Me.cmdNext.TabIndex = 3
      Me.cmdNext.Text = "Next"
      "
      "cmdPrevious
      "
      Me.cmdPrevious.Location = New System.Drawing.Point(56, 24)
      Me.cmdPrevious.Name = "cmdPrevious"
      Me.cmdPrevious.TabIndex = 2
      Me.cmdPrevious.Text = "Previous"
      "
      "txtSelect
      "
      Me.txtSelect.BackColor = System.Drawing.SystemColors.Info
      Me.txtSelect.Location = New System.Drawing.Point(8, 64)
      Me.txtSelect.Multiline = True
      Me.txtSelect.Name = "txtSelect"
      Me.txtSelect.ReadOnly = True
      Me.txtSelect.Size = New System.Drawing.Size(320, 56)
      Me.txtSelect.TabIndex = 2
      Me.txtSelect.Text = ""
      "
      "locateGroupBox
      "
      Me.locateGroupBox.Controls.AddRange(New System.Windows.Forms.Control() {Me.txtSelect, Me.cmdSelect, Me.cboSelect})
      Me.locateGroupBox.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
      Me.locateGroupBox.Location = New System.Drawing.Point(8, 8)
      Me.locateGroupBox.Name = "locateGroupBox"
      Me.locateGroupBox.Size = New System.Drawing.Size(336, 128)
      Me.locateGroupBox.TabIndex = 0
      Me.locateGroupBox.TabStop = False
      Me.locateGroupBox.Text = "Locate Element"
      "
      "cmdSelect
      "
      Me.cmdSelect.Location = New System.Drawing.Point(8, 32)
      Me.cmdSelect.Name = "cmdSelect"
      Me.cmdSelect.TabIndex = 1
      Me.cmdSelect.Text = "Select"
      "
      "FrmPathNavigator
      "
      Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
      Me.ClientSize = New System.Drawing.Size(352, 413)
      Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.trePath, Me.navigateGroupBox, Me.locateGroupBox})
      Me.Name = "FrmPathNavigator"
      Me.Text = "Path Navigator"
      Me.navigateGroupBox.ResumeLayout(False)
      Me.locateGroupBox.ResumeLayout(False)
      Me.ResumeLayout(False)
   End Sub
#End Region
   " traverse to first child
   Private Sub cmdFirstChild_Click( _
      ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles cmdFirstChild.Click
      Dim newTreeNode As TreeNode
      If xPath.MoveToFirstChild Then
         newTreeNode = New TreeNode() " create new node
         DetermineType(newTreeNode, xPath)
         tree.Nodes.Add(newTreeNode)
         tree = newTreeNode " assign tree newTreeNode
         trePath.ExpandAll()
         trePath.Refresh()
         trePath.SelectedNode = tree
      Else 
         Console.WriteLine("Current Node has no children.")
      End If
   End Sub " cmdFirstChild_Click
   Private Sub cmdParent_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles cmdParent.Click
      If xPath.MoveToParent Then
         tree = tree.Parent
         Dim count As Integer = tree.GetNodeCount(False)
         Dim i As Integer
         For i = 0 To count - 1
            tree.Nodes.Remove(tree.FirstNode)
         Next
         trePath.ExpandAll()
         trePath.Refresh()
         trePath.SelectedNode = tree
      Else 
         Console.WriteLine("Current node has no parent.", "", _
            MessageBoxButtons.OK, MessageBoxIcon.Information)
      End If
   End Sub " cmdParent_Click
   Private Sub cmdNext_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles cmdNext.Click
      Dim newTreeNode As TreeNode = Nothing
      Dim newNode As TreeNode = Nothing
      If xPath.MoveToNext Then
         newTreeNode = tree.Parent " get parent node
         newNode = New TreeNode() " create new node
         DetermineType(newNode, xPath)
         newTreeNode.Nodes.Add(newNode)
         tree = newNode
         trePath.ExpandAll()
         trePath.Refresh()
         trePath.SelectedNode = tree
      Else 
         Console.WriteLine("Current node is last sibling.", "", _
            MessageBoxButtons.OK, MessageBoxIcon.Information)
      End If
   End Sub 
   Private Sub cmdPrevious_Click( _
      ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles cmdPrevious.Click
      Dim parentTreeNode As TreeNode = Nothing
      If xPath.MoveToPrevious Then
         parentTreeNode = tree.Parent " get parent node
         " delete current node
         parentTreeNode.Nodes.Remove(tree)
         " move to previous node
         tree = parentTreeNode.LastNode
         " update TreeView control
         trePath.ExpandAll()
         trePath.Refresh()
         trePath.SelectedNode = tree
      Else " if current node has no previous siblings
         MessageBox.Show("Current node is first sibling.", "", _
            MessageBoxButtons.OK, MessageBoxIcon.Information)
      End If
   End Sub " cmdPrevious_Click
   " process cmdSelect_Click event
   Private Sub cmdSelect_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles cmdSelect.Click
      Dim iterator As XPathNodeIterator " enables node iteration
      " get specified node from ComboBox
      Try
         iterator = xPath.Select(cboSelect.Text)
         DisplayIterator(iterator) " print selection
         " catch invalid expressions
      Catch argumentException As System.ArgumentException
         MessageBox.Show(argumentException.Message, "Error", _
            MessageBoxButtons.OK, MessageBoxIcon.Error)
      End Try
   End Sub " cmdSelect_Click
   " print values for XPathNodeIterator
   Private Sub DisplayIterator( _
      ByVal iterator As XPathNodeIterator)
      txtSelect.Clear()
      " prints selected node"s values
      While iterator.MoveNext
         txtSelect.Text &= iterator.Current.Value.Trim & vbCrLf
      End While
   End Sub " DisplayIterator
   " determine if TreeNode should display current node
   " name or value
   Private Sub DetermineType(ByVal node As TreeNode, _
      ByVal xPath As XPathNavigator)
      " determine NodeType
      Select Case xPath.NodeType
         Case XPathNodeType.Element " if Element, get its name
            " get current node name, and remove whitespaces
            node.Text = xPath.Name.Trim
         Case Else  " obtain node values
            " get current node value and remove whitespaces
            node.Text = xPath.Value.Trim
      End Select
   End Sub
End Class

" *************************************************************
" * (C) Copyright 2002 by Deitel & Associates, Inc.           *
" *     and Prentice Hall.                                    *
" * All Rights Reserved.                                      *
" *                                                           *
" * DISCLAIMER: The authors and publisher of this book have   *
" * used their best efforts in preparing the book. These      *
" * efforts include the development, research, and testing of *
" * the theories and programs to determine their              *
" * effectiveness. The authors and publisher make no warranty *
" * of any kind, expressed or implied, with regard to these   *
" * programs or to the documentation contained in these books.*
" * The authors and publisher shall not be liable in any event*
" * for incidental or consequential damages in connection     *
" * with, or arising out of, the furnishing, performance, or  *
" * use of these programs.                                    *
" *************************************************************