Salient Solutions

Accessing app.config/web.config from T4 template - Take 2

In a previous post, Accessing app.config/web.config from T4 template, I provided an include template to provide access to the configuration file. In this post I present a stand-alone template, umm, template that you can stuff your own code into.

ConfigEnabledTemplate.tt

<#@ template inherits="Microsoft.VisualStudio.TextTemplating.VSHost.ModelingTextTransformation" language="C#v3.5" debug="true" hostSpecific="true" #>
<#@ output extension=".cs" #>
<#@ assembly name="EnvDTE" #>
<#@ assembly name="System.Configuration.dll" #>
<#@ Assembly Name="System.Core.dll" #>
<#@ import namespace="System" #>
<#@ import namespace="System.Configuration" #>
<#@ import namespace="System.Text.RegularExpressions" #>
<#   

// <copyright file="c" company="Sky Sanders">
// 
// This source is a Public Domain Dedication. 
// 
// http://salientt4.codeplex.com
// 
// Attribution is appreciated.
// 
// </copyright> 


	/// <summary>
	/// This template can serve as a starting point for a standalone template with
	/// access to the hosting project and app/web configuration file.
	/// </summary> 
	

	// USAGE EXAMPLES

	// get a connection string
	ConnectionStringSettings cs = ConnectionStrings["northwind"];
	
	// get an appSetting value
	string myAppSetting = AppSettings["myAppSetting"].Value;
	
	// use a helper method to get value or default
	string absentAppSetting = (string)AppSettingValueOrDefault("xxx","default value for absent setting");
	
	// get a project property
	string rootNamespace = Project.Properties.Item("RootNamespace").Value.ToString();
	
	// your logic here
 
 	
#>
	
// your boilerplate code here
namespace <#= rootNamespace #>
{
	public class InlineT4ConfigAccessDemo
	{
		// Northwind connection string = <#= cs.ConnectionString #>
		// myAppSetting = <#= myAppSetting #>
		// absentAppSetting = <#= absentAppSetting #>
		// rootNamespace = <#= rootNamespace #>
	
	}
}



<#+  
	// Configuration Accessor Helpers
	
	private static Configuration _config;
	private static EnvDTE.Project _project;
	
	/// <summary>
	/// Example:
	/// <code>
	/// string cs = ConnectionStrings["myConnectionString"].ConnectionString;
	/// </code>
	/// </summary>
	private ConnectionStringSettingsCollection ConnectionStrings
	{
		get { return Configuration.ConnectionStrings.ConnectionStrings;}
	}
	
	/// <summary>
	/// Example:
	/// <code>
	/// string setting = AppSettings["mySetting"].Value;
	/// </code>
	/// </summary>
	private KeyValueConfigurationCollection AppSettings
	{
		get { return Configuration.AppSettings.Settings; }
	}

	
	/// <summary>
	/// Returns value of setting, if present, otherwise defaultValue
	/// </summary>
	/// <param name="key">appSettings key</param>
	/// <param name="defaultValue">value to return if setting is absent</param>
	/// <returns></returns>
 	private object AppSettingValueOrDefault(string key,object defaultValue)
	{
		if (AppSettings[key] != null)
		{
			return AppSettings[key].Value;
		}			
		return defaultValue;
	}
	
	
	/// <summary>
	/// The app/web config file for hosting project, if any
	/// </summary>
	private Configuration Configuration
	{
		get 
		{
			if(_config==null)
			{
				string configurationFilename=null;	
				
				// examine each project item's filename looking for app.config or web.config
				foreach (EnvDTE.ProjectItem item in Project.ProjectItems)
				{
					if (Regex.IsMatch(item.Name,"(app|web).config",RegexOptions.IgnoreCase))
					{
						// TODO: try this with linked files. is the filename pointing to the source?
						configurationFilename=item.get_FileNames(0);
						break;
					}
				}

				if(!string.IsNullOrEmpty(configurationFilename))
				{
					// found it, map it and return it
					ExeConfigurationFileMap configFile = null;
					configFile = new ExeConfigurationFileMap();
					configFile.ExeConfigFilename=configurationFilename;
					_config = System.Configuration.ConfigurationManager.OpenMappedExeConfiguration(configFile, ConfigurationUserLevel.None);
				}	
			}
			return _config;
		}
	}
	
	/// <summary>
	/// The hosting project.
	/// </summary>
	private EnvDTE.Project Project
	{
		get
		{
			if(_project==null)
			{
				// Get the instance of Visual Studio that is hosting the calling file
				EnvDTE.DTE env = (EnvDTE.DTE)((IServiceProvider)this.Host).GetService(typeof(EnvDTE.DTE));
				// Gets an array of currently selected projects. Since you are either in this file saving it or
				// right-clicking the item in solution explorer to invoke the context menu it stands to reason
				// that there is 1 ActiveSolutionProject and that it is the parent of this file....
				_project = (EnvDTE.Project)((Array)env.ActiveSolutionProjects).GetValue(0);
			}
			return _project;
		}
	}

#>

Print | posted on Sunday, January 24, 2010 5:51 PM |