Reading Elements

Reading Elements

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Microsoft Visual Studio 2008/.NET Framework 3.5

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.NET Framework Developer's Guide

Reading Elements

The following table describes the methods and properties that the XmlReader class provides for processing elements. After the XmlReader is positioned on an element, the node properties, such as Name, reflect the element values. In addition to the members described below, any of the general methods and properties of the XmlReader class can also be used to process elements. For example, you can use the ReadInnerXml method to read the contents of an element.

Note:
These methods include an initial call to the MoveToContent method.

Member name	Description
IsStartElement	Checks if the current node is a start tag or an empty element tag.
ReadStartElement	Checks that the current node is an element and advances the reader to the next node.
ReadEndElement	Checks that the current node is an end tag and advances the reader to the next node.
ReadElementString	Reads a text-only element.
ReadToDescendant	Advances the XmlReader to the next descendant element with the specified name.
ReadToNextSibling	Advances the XmlReader to the next sibling element with the specified name.
IsEmptyElement	Checks if the current element has an empty element tag. This property enables you to determine the difference between the following: <item num="123"/> (IsEmptyElement is true.) <item num="123"> (IsEmptyElement is false, although element content is empty.) In other words, IsEmptyElement simply reports whether or not the element in the source document has an end element tag.

Examples

The following code reads elements using the ReadStartElement and ReadString methods.

Visual Basic

Using reader As XmlReader = XmlReader.Create("book3.xml")               
  ' Parse the XML document.  ReadString is used to 
  ' read the text content of the elements.
  reader.Read()
  reader.ReadStartElement("book")
  reader.ReadStartElement("title")
  Console.Write("The content of the title element:  ")
  Console.WriteLine(reader.ReadString())
  reader.ReadEndElement()
  reader.ReadStartElement("price")
  Console.Write("The content of the price element:  ")
  Console.WriteLine(reader.ReadString())
  reader.ReadEndElement()
  reader.ReadEndElement()            
End Using

using (XmlReader reader = XmlReader.Create("book3.xml")) {

  // Parse the XML document.  ReadString is used to 
  // read the text content of the elements.
  reader.Read(); 
  reader.ReadStartElement("book");  
  reader.ReadStartElement("title");   
  Console.Write("The content of the title element:  ");
  Console.WriteLine(reader.ReadString());
  reader.ReadEndElement();
  reader.ReadStartElement("price");
  Console.Write("The content of the price element:  ");
  Console.WriteLine(reader.ReadString());
  reader.ReadEndElement();
  reader.ReadEndElement();

}

The following code processes elements by using a While loop.

Visual Basic

While reader.Read()
  If reader.IsStartElement() Then
    If reader.IsEmptyElement Then
      Console.WriteLine("<{0}/>", reader.Name)
    Else
      Console.Write("<{0}> ", reader.Name)
      reader.Read() ' Read the start tag.
      If reader.IsStartElement() Then ' Handle nested elements.
        Console.Write(vbCr + vbLf + "<{0}>", reader.Name)
      End If
      Console.WriteLine(reader.ReadString()) 'Read the text content of the element.
    End If
  End If
End While

while (reader.Read()) {
  if (reader.IsStartElement()) {
    if (reader.IsEmptyElement)
      Console.WriteLine("<{0}/>", reader.Name);
    else {
      Console.Write("<{0}> ", reader.Name);
      reader.Read(); // Read the start tag.
      if (reader.IsStartElement())  // Handle nested elements.
        Console.Write("\r\n<{0}>", reader.Name);
      Console.WriteLine(reader.ReadString());  //Read the text content of the element.
    }
  } 
}

Concepts

Reading XML with the XmlReader

Tags

: contentbug (x) contentbugfix (x) Add a tag

XML Sample using PowerShell

Thomas Lee | Edit | Show History

<#
.SYNOPSIS
    This script reads a simple XML file and prints the results
.DESCRIPTION
    This script is a re-write of an XML C# MSDN Sample.
.NOTES
    File Name  : get-xmlfilecontents.ps1
     Author     : Thomas Lee - tfl@psp.co.uk
     Requires   : PowerShell V2 CTP3
     Books3.xml = 
       <book>
         <title>C# Introduction</title>
         <price>20</price>
       </book>
.LINK
    This script posted to:
        http://www.pshscripts.blogspot.com
    MSDN Sample posted at:
        http://msdn.microsoft.com/en-us/library/t9bfea29.aspx
.EXAMPLE
    PSH [C:\foo]: .\Get-XMLFileContents.PS1
    The content of the title element: C# Introduction
    The content of the price element: 20
 
#>
 
##
# Start of Script
##
 
# Create XML Reader
$reader = [system.Xml.XmlReader]::Create("C:\foo\book3.xml")
 
# Parse the XML document.  ReadString is used to 
# read the text content of the elements.
$result=$reader.Read()
 
# Read/Display title
$reader.ReadStartElement("book")
$reader.ReadStartElement("title")   
"The content of the title element: {0}" -f $reader.ReadString()
$reader.ReadEndElement()
 
# Read and display price
$reader.ReadStartElement("price")
"The content of the price element: {0}" -f $reader.ReadString()
$reader.ReadEndElement()
$reader.ReadEndElement()
# End of Script