Transforming Visual Studio .NET Projects into NANT files using XSLT and .NET

Listing 3 - Using the XslTransform class to transform the csproj file

// read the input file to be transformed
XPathDocument xpathdocument = new XPathDocument(browserProject.FileName);
// read the xslt transform to perform on the input file
XslTransform xslt = new XslTransform();
xslt.Load(browserXSLT.FileName);
// create a file for output.
XmlTextWriter writer = new XmlTextWriter(browserNantOutput.FileName, Encoding.Unicode);
writer.Formatting=Formatting.Indented;
// perform the transform on the input file and write out the result transformation
xslt.Transform(xpathdocument, null, writer, null);
writer.Close();
// display the output in the edit box
StreamReader sr = new StreamReader(browserNantOutput.FileName);
txtOutput.Text = sr.ReadToEnd();
sr.Close();

Persisting Data in the App.Config File

One thing I wanted to try to do in this project was to persist the fields in the dialog by writing them to the App.Config File. Upon finding the System.Configuration.ConfigurationSettings.AppSettings class, I thought, Great! .NET provides a nice convenient way of persisting data to the configuration file. Then I ran into the snag of actually trying to use this class to persist data to the config file. I found that the class reads the data fine out of the file. The problem is that the class cannot write the data to the keys. What is even more confusing is that a Set method is even provided in the AppSettings class, but the class doesn't actually allow you to use this method. It was time to search and see if anyone else was having the same problem. In my research and with a little coding, I ended up creating the following class in Listing 5 to solve the problem. Basically the class ConfigHandler uses the convenient System.Xml namespace and XPath to read and write the keys and values in a configuration file. We can use the XmlDocument class to Load the configuration file and then the XPath query allows us the select the desired node out of the XmlDocument. Once we have the XmlNode of interest we can either read or write to it.The XPathquery,
/configuration/appSettings/add[@key = <key> allows us to select a single node with the particular <key> out of the Xml Hierarchy configuration->appsettings->add.

Listing 4 - App.Config file containing persistent form values

<?xml version="1.0" encoding="utf-8"?>
<configuration>
<appSettings>
<!-- User application and configured property settings go here.-->
<!-- Example: <add key="settingName" value="settingValue"/> -->
<add key="browserProject.FileName" value="C:\NAnts\tests\NAnt.Tests.csproj" />
<add key="browserNantOutput.FileName" value="C:\temp0" />
<add key="browserXSLT.FileName" value="C:\NAnts\vsconvert.xsl" />
</appSettings>
</configuration>

Listing 5 - Class to handle persistence in the App.Config file

public class ConfigHandler
{
public ConfigHandler()
{
}
/// <summary>
/// This is the configuration file path property. Set this before using this class
/// </summary>
static string _configurationPath = "App.Config";
static public string ConfigurationPath
{
get
{
return _configurationPath ;
}
set
{
_configurationPath = value ;
}
}
/// <summary>
/// Replace the key and value pair in the configuration file
/// </summary>
/// <param name="key"></param>
/// <param name="val"></param>
static public void replaceConfigSettings(string key, string val)
{
XmlDocument xDoc = new XmlDocument();
string sFileName = _configurationPath;
try
{
// load the configuration file
xDoc.Load(sFileName);
// find the node of interest containing the key using XPATH
XmlNode theNode = xDoc.SelectSingleNode(@"/configuration/appSettings/add[@key = '" + key + "\']");
// Set the new value for the node
if (theNode != null)
theNode.Attributes["value"].Value = val;
// lop off file prefix if it exists
if(sFileName.StartsWith(file:///))
sFileName = sFileName.Remove(0,8);
// save the new configuration settings
xDoc.Save(sFileName);
xDoc = null;
}
catch(Exception ex)
{
#if DEBUG
System.Windows.Forms.MessageBox.Show("replaceConfigSettings()"+ex.Message);
#else
System.Windows.Forms.MessageBox.Show("Unable to save changes");
#endif
xDoc = null;
}
}
/// <summary>
/// Retrieve the configuration value given the key
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
static public string GetConfigSetting(string key)
{
XmlDocument xDoc = new XmlDocument();
string sFileName = _configurationPath;
// make sure the file exists, if not return
if (File.Exists(sFileName) == false)
{
return "";
}
try
{
// load the configuration file
xDoc.Load(sFileName);
// find the node of interest from the key
XmlNode theNode = xDoc.SelectSingleNode(@"/configuration/appSettings/add[@key = '" + key + "\']");
// retrieve the nodes value if it exists
if (theNode != null)
return theNode.Attributes["value"].Value;
xDoc = null;
}
catch(Exception ex)
{
#if DEBUG
System.Windows.Forms.MessageBox.Show("replaceConfigSettings()"+ex.Message);
#else
System.Windows.Forms.MessageBox.Show("Unable to load changes");
#endif
xDoc = null;
}
return "";
}
}

Conclusion

.NET gives us a lot of power over XML technologies with the System.Xml, System.Xml.Xsl, and System.Xml.XPath namespaces. With these namespaces and the classes contained within, we can manipulate Xml by running Xsl Transforms on files and performing XPath queries. Because both Nant and VS.NET projects are XML files, we can utilize the power of Xsl to convert between the two.

NAnt and NDoc are two very powerful Open Source tools that you can add to your .NET arsenal. If you are going to begin using NAnt, I encourage you to look at the simple tutorial provided on sourceforge to begin your NAnt journey. In the meantime, if you run into a situation where think you may not be able to do it with Visual Studio.NET,never say CAn't, when you may be able to do it with NAnt.