An extension for a Configuration Settings class in .NET

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Introduction

In the System.Configuration namespace you will find a sealed class called ConfigurationSettings which provides access to a static NameValueCollection entitled AppSettings.  This ConfigurationSettings class allows you to access information stored in an XML-based configuration file.  This file is typically titled the name of your executable followed by a ".config" file extension.  The main inherent problem with this class is that your strictly only allowed to read values from configuration file through this class, no updating method is provided.  I have addressed this issue below in the following ConfigSettings class.  I have also updated the class to implement the IConfigurationSectionHandler interface which I plan on detailing within this article as soon as I have more time (Thanks Heath for the suggestion).  Reflector was a big help along with simply reading the documentation.  As always, if I left something out, please leave a message at the bottom.  Hope this is of some help.

The following namespaces are required:

using System;
using System.IO;
using System.Xml;
using System.Reflection;
using System.Collections;
using System.Globalization;
using System.Configuration;
using System.Collections.Specialized;

The class looks like the following:

namespace Configuration
{

    public class ConfigSettingsSectionHandler : IConfigurationSectionHandler
    {
	static ConfigSettingsSectionHandler(){}

	public object Create(object parent, object configContext, 
                                                   System.Xml.XmlNode section)
	{
	    NameValueCollection col = new NameValueCollection(
	    new CaseInsensitiveHashCodeProvider(CultureInfo.InvariantCulture), 
		   new CaseInsensitiveComparer(CultureInfo.InvariantCulture));

		foreach(XmlNode node in section.ChildNodes)
		{
			switch(node.Name)
			{	
				case "add":
				col.Add(node.Attributes["key"].Value, 
					node.Attributes["value"].Value);
				break;
			}
		}
		return col;
	  }
     }
	

public class ConfigSettings	
{
	private string _configfilename, _query, _sectionName;
	private XmlDocument _doc;
	private XmlTextWriter _writer;
	private XmlNodeList _nodes;
	private XmlElement  _appsettings, _node;
	private XmlAttribute _attr1, _attr2;
	private bool _bFileExists;

	public ConfigSettings()
	{
		if(File.Exists(Assembly.GetExecutingAssembly().ToString() + 
                                                               ".exe.config"))
		{
			this.ConfigFileName = 
                   Assembly.GetExecutingAssembly().ToString() + ".exe.config";
			_bFileExists = true;
		}
		else
		{
			_bFileExists = false;
		}
	}

	public ConfigSettings(string ConfigFileName)
	{
		if(File.Exists(ConfigFileName))
		{
			this.ConfigFileName = ConfigFileName;
			_bFileExists = true;
		}
		else
		{
			_bFileExists = false;
		}
	}

		
	public NameValueCollection GetConfig()
	{
		return (NameValueCollection)ConfigurationSettings.GetConfig(
                                                                 SectionName);
	}

	public NameValueCollection GetConfig(string SectionName)
	{
	    return (NameValueCollection)ConfigurationSettings.GetConfig(
                                                                 SectionName);
	}

	public string GetValue(string AttributeName)
	{
		NameValueCollection col = this.GetConfig();
		if(col[AttributeName] != null)
		       return Convert.ToString(col[AttributeName].ToString());
		else
			return String.Empty;
	}

	public void SetValue(string AttributeName, string Value)
	{
	        XmlDocument = new XmlDocument();
		XmlDocument.Load(this.ConfigFileName);
	        Query = "configuration/" + SectionName;
		AppSettingsNode = 
                    (XmlElement)this.XmlDocument.SelectSingleNode(this.Query);
		if(AppSettingsNode == null)
			return;
		Query += "/add[@key='" + AttributeName.ToString() + "']";
		XmlNodeList = this.XmlDocument.SelectNodes(this.Query);
		if(XmlNodeList.Count > 0)
			Node = (XmlElement)XmlNodeList[0];
		else
		{
			Node = this.XmlDocument.CreateElement("add");
			XmlAttribute1 = 
                                      this.XmlDocument.CreateAttribute("key");
			XmlAttribute1.Value = AttributeName.ToString();
			Node.Attributes.SetNamedItem(XmlAttribute1);
			XmlAttribute2 = 
                                    this.XmlDocument.CreateAttribute("value");
			Node.Attributes.SetNamedItem(XmlAttribute2);
			AppSettingsNode.AppendChild(Node);
		}
		Node.Attributes["value"].Value = Value.ToString();
		this.XmlDocument.Save(this.ConfigFileName);
	}


	public void CreateConfigFile(string ConfigFileName, 
                                                           string sectionName)
	{
	        FileStream file = new FileStream(ConfigFileName, 
                                                   System.IO.FileMode.Create);
		file.Close();
		Writer = new XmlTextWriter(ConfigFileName, 
                                                System.Text.Encoding.Unicode);
		Writer.Formatting = Formatting.Indented;
		Writer.WriteRaw("<?xml version=\"1.0\" ?>\n");
		Writer.WriteRaw("<configuration>\n");
		Writer.WriteRaw("<configSections>\n");
		string str = String.Format("<section type="{1}" name="{0}" />\n", 
                       "\"" + sectionName.ToString() + "\"",
             "\"Configuration.ConfigSettingsSectionHandler, Configuration\"");
		Writer.WriteRaw(str.ToString());
		Writer.WriteRaw("</configSections>\n");
		Writer.WriteRaw("<" + sectionName.ToString() + ">\n");
		Writer.WriteRaw("</" ? + sectionName.ToString()>\n");
		Writer.Flush();
		Writer.Close();
		}
	}

        public string ConfigFileName
	{
		get{ return _configfilename;}
		set{ _configfilename = value;}
	}
	public XmlDocument XmlDocument
	{
		get{ return _doc;}
		set{ _doc = value;}
	}
	public XmlTextWriter Writer
	{
		get{ return _writer;}
		set{ _writer = value;}
	}
	public XmlNodeList XmlNodeList
	{
		get{ return _nodes;}
		set{ _nodes = value;}
	}
	public XmlElement AppSettingsNode
	{
		get{ return _appsettings;}
		set{ _appsettings = value;}
	}
	public XmlElement Node
	{
		get{ return _node;}
		set{ _node = value;}
	}
	public string Query
	{
		get{ return _query;}
		set{ _query = value;}
	}
	public XmlAttribute XmlAttribute1
	{
		get{ return _attr1;}
		set{ _attr1 = value;}
	}
	public XmlAttribute XmlAttribute2
	{
		get{ return _attr2;}
		set{ _attr2 = value;}
	}
	public string SectionName
	{
		get{ return _sectionName;}
		set{ _sectionName = value;}
	}
	public bool FileExists
	{
		get{return _bFileExists;}
		set{_bFileExists = value;}
	}

}

Using the class

To use the class you will simply do one of the following:

private ConfigSettings config = new ConfigSettings();

and then just use either the GetConfig(), GetValue(), SetValue() methods as such:

  private void Form1_Load(object sender, System.EventArgs e)
  {
     config.ConfigFileName = "Test.exe.config";
     config.SectionName = "ApplicationData";
     string height = config.GetValue("Height");
     if(height != String.Empty)
         this.Height = Convert.ToInt32(height.ToString());

     // or return the whole collection of a particular section.


     NameValueCollection collection = config.GetConfig("ApplicationData");
     if(collection["Width"] != null)
          this.Width = Convert.ToInt32(collection["Width"].ToString());
}

  private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)
  {
        config.SectionName = "ApplicationData";
        config.SetValue("Height", this.Height.ToString());
        config.SetValue("Width", this.Width.ToString());
  }

Conclusion

I just thought I would post the latest updates, there are still many changes to come including a code clean-up as well as more methods to interact with the config file.  Let me know what you think.