Reading an XML file using .NET

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Introduction

In this article one will see how we can read and XML file it our ASP.NET application, this trick is use full for making custom configuration files for your application or just reading data stored in an xml file.

Overview

This code uses the XmlTextReader object to read the disk file into the XmlDocument object. the XmlTextReader object has very similar functionality to the StreamReader and BinaryReader objects, except that it is specifically designed to read XML file. The XmlTextReader object also has other XML-specific features. For example the WhitespaceHandling property setting in the code tells it not to create nodes for extra whitespace in the XML file.

The code uses the DocumentElement property of the XmlDocument object to find the node at the root of the tree representation of the XML document. After that, we just recursively call the procedure that adds information about the node to the ListBox control.

The code also deals with attributes. Attribues nodes are not included in the ChildNodes collection of a node in the XmlDocument object. Instead, you can use the Attributes property of the XmlNode object to get a collection of attribute nodes only. The code uses an XmlNamedNodeMap object to hold this collection; this object can hold an arbitrary collection of XmlNode objects of any type.

Code listing

    private void btnLoad_Click(object sender, System.EventArgs e)
    {
      XmlTextReader reader = new XmlTextReader(
        Server.MapPath("mycompany.xml"));
      
      reader.WhitespaceHandling = WhitespaceHandling.None;
      XmlDocument xmlDoc = new XmlDocument();
      //Load the file into the XmlDocument
      xmlDoc.Load(reader);
      //Close off the connection to the file.
      reader.Close();
      //Add and item representing the document to the listbox
      lbNodes.Items.Add("XML Document");
      //Find the root nede, and add it togather with its childeren
      XmlNode xnod = xmlDoc.DocumentElement;
      AddWithChildren(xnod,1);
    }
    
    private void AddWithChildren(XmlNode xnod, Int32 intLevel)
    {
      //Adds a node to the ListBox, togather with its children.
      //intLevel controls the depth of indenting
      XmlNode xnodWorking;
      String strIndent = new string(' ',2 * intLevel);
      //Get the value of the node (if any)
      string strValue = (string) xnod.Value;
      if(strValue != null)
      {
        strValue = " : " + strValue;
      }
      //Add the node details to the ListBox
      lbNodes.Items.Add(strIndent + xnod.Name + strValue);

      //For an element node, retrive the attributes
      if (xnod.NodeType == XmlNodeType.Element)
      {
        XmlNamedNodeMap mapAttributes = xnod.Attributes;
        //Add the attributes to the ListBox
        foreach(XmlNode xnodAttribute in mapAttributes)
        {
          lbNodes.Items.Add(strIndent + " " + xnodAttribute.Name + 
            " : " + xnodAttribute.Value);
        }
        //If there are any child node, call this procedrue recursively
        if(xnod.HasChildNodes)
        {
          xnodWorking = xnod.FirstChild;
          while (xnodWorking != null)
          {
            AddWithChildren(xnodWorking, intLevel +1);
            xnodWorking = xnodWorking.NextSibling;
          }
        }
      }
    }
  }

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