sdk/samples/all in on code/Visual Studio 2008/VBXPath/MainModule.vb

   1 '****************************** Module Header ******************************\
   2 ' Module Name:  Program.cs
   3 ' Project:      VBXPath
   4 ' Copyright (c) Microsoft Corporation.
   5 '
   6 ' This sample project shows how to use XPathDocument class to load the XML file
   7 ' and manipulate. It includes two main parts, XPathNavigator usage and XPath
   8 ' Expression usage. The first part shows how to use XPathNavigator to navigate
   9 ' through the whole document, read its content. The second part shows how to
  10 ' used XPath expression to filter information and select it out.
  11 '
  12 ' This source is subject to the Microsoft Public License.
  13 ' See http://www.microsoft.com/opensource/licenses.mspx#Ms-PL.
  14 ' All other rights reserved.
  15 '
  16 ' THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
  17 ' EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
  18 ' WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
  19 '***************************************************************************/
  20
  21 #Region "Imports directives"
  22
  23 Imports System.Xml.XPath
  24
  25 #End Region
  26
  27
  28 Module MainModule
  29
  30     Sub Main()
  31         'Initialize XPathDocument and XPathNavigator
  32         Dim nav As XPathNavigator
  33         Dim xPathNavigator As XPathNavigator = New XPathDocument("books.xml").CreateNavigator
  34
  35         'Navigate through the document
  36         xPathNavigator.MoveToRoot()
  37         xPathNavigator.MoveToFirstChild()
  38         If ((xPathNavigator.NodeType = XPathNodeType.Element) AndAlso xPathNavigator.HasChildren) Then
  39             xPathNavigator.MoveToFirstChild()
  40             Do
  41                 If xPathNavigator.HasAttributes Then
  42                     Console.WriteLine(("Book ID: " & xPathNavigator.GetAttribute("id", "")))
  43                 End If
  44                 If xPathNavigator.HasChildren Then
  45                     xPathNavigator.MoveToFirstChild()
  46                     Do
  47                         Console.Write(ChrW(9) & "{0}:" & ChrW(9) & "{1}" & ChrW(13) & ChrW(10), xPathNavigator.Name, xPathNavigator.Value)
  48                     Loop While xPathNavigator.MoveToNext
  49                     xPathNavigator.MoveToParent()
  50                 End If
  51             Loop While xPathNavigator.MoveToNext
  52         End If
  53
  54         'Use XPath Expression to select out the book with ID bk103
  55         Console.WriteLine("Use XPath Expression to select out the book with ID bk103:")
  56         Dim expression As XPathExpression = xPathNavigator.Compile("/catalog/book[@id='bk103']")
  57         Dim iterator As XPathNodeIterator = xPathNavigator.Select(expression)
  58         Do While iterator.MoveNext
  59             nav = iterator.Current.Clone
  60             Console.WriteLine(("Book ID: " & nav.GetAttribute("id", "")))
  61             If nav.HasChildren Then
  62                 nav.MoveToFirstChild()
  63                 Do
  64                     Console.Write(ChrW(9) & "{0}:" & ChrW(9) & "{1}" & ChrW(13) & ChrW(10), nav.Name, nav.Value)
  65                 Loop While nav.MoveToNext
  66             End If
  67         Loop
  68
  69         'Use XPath Expression to select out all books whose price are more than 10
  70         Console.WriteLine(ChrW(13) & ChrW(10) & "Use XPath Expression to select out all books whose price are more than 10:")
  71         expression = xPathNavigator.Compile("/catalog/book[price>10]")
  72         iterator = xPathNavigator.Select(expression)
  73         Do While iterator.MoveNext
  74             nav = iterator.Current.Clone
  75             Console.WriteLine(("Book ID: " & nav.GetAttribute("id", "")))
  76             If nav.HasChildren Then
  77                 nav.MoveToFirstChild()
  78                 Do
  79                     If (nav.Name = "title") Then
  80                         Console.Write(ChrW(9) & "{0}:" & ChrW(9) & "{1}" & ChrW(13) & ChrW(10), nav.Name, nav.Value)
  81                     End If
  82                     If (nav.Name = "price") Then
  83                         Console.Write(ChrW(9) & "{0}:" & ChrW(9) & "{1}" & ChrW(13) & ChrW(10), nav.Name, nav.Value)
  84                     End If
  85                 Loop While nav.MoveToNext
  86             End If
  87         Loop
  88
  89         'Use XPath Expression to calculate the average price of all books.
  90         Console.WriteLine(ChrW(13) & ChrW(10) & "Use XPath Expression to calculate the average price of all books:")
  91         expression = xPathNavigator.Compile("sum(/catalog/book/price) div count(/catalog/book/price)")
  92         Dim averagePrice As String = xPathNavigator.Evaluate(expression).ToString
  93         Console.WriteLine("The average price of the books are {0}", averagePrice)
  94
  95         'End. Read a char to exit
  96         Console.WriteLine("Input any key to quit the sample application")
  97         Console.ReadLine()
  98
  99     End Sub
 100
 101 End Module