Last week I wanted to generate a object wrapper around the <appSettings> section in my web.config/app.config file and after doing the same thing over and over again by generating a public read-only property for each setting, I decided to use T4 to read the <appSettings> section and generate a class all the properties that would become the wrapper around the ConfigurationManager.AppSettings[“…”] calls to retrieve the settings. To my surprise, this was pretty easy to do. I did a C# and VB.Net version and here is the C# version of the T4 template.

<#@ assembly name="System.Core" #>
<#@ assembly name="System.Xml" #>
<#@ assembly name="System.Xml.Linq" #>
<#@ import namespace="System" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.IO" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Xml.Linq" #>
<#@ import namespace="Microsoft.VisualBasic" #>
<#@ template language="VBv3.5" debug="True" hostspecific="True"  #>
<#@ output extension=".g.cs" #>
<#
	Dim projectNamespace as String = "SettingsGenerator"
	Dim fileName as String = "app.config"
	Dim path as String = ""

	Try
		path = Host.ResolvePath(fileName)
	Catch
		Try
			If fileName.ToLower() = "app.config" then
				fileName = "web.config"
			Else If fileName.ToLower() = "web.config" then
				fileName = "app.config"
			End If
			path = Host.ResolvePath(fileName)
		Catch
			path = "<< App.config or Web.config not found within the project >>"
		End Try
	End Try
#>
//------------------------------------------------------------------------------
// FileName = <#= path #>
// Generated at <#= Now.ToLocaltime() #>
//
// <auto-generated>
//     This code was generated by a tool.
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
//
//	  NOTE: Please use the Add a Reference to System.Configuration assembly if
//	        you get compile errors with ConfigurationManager
// </auto-generated>
//------------------------------------------------------------------------------

using System.Configuration;

public static class AppSettings {

<#= RenderApplicationSettings(path) #>
}

<#+ 

	Public Shared Function RenderApplicationSettings(ByVal path as String) as String
		If Not File.Exists(path) Then Return ""

		Dim sb as New StringBuilder()

		Dim doc as XDocument = XDocument.Load(path)

		For Each result as XElement in doc...<appSettings>.<add>
			sb.Append(vbTab)
			sb.Append("public static string " + result.@key + "{")
			sb.AppendLine()
			sb.AppendLine(vbTab + vbTab + "get {")
			sb.AppendFormat("{0}return ConfigurationManager.AppSettings[""{1}""];{2}", vbTab + vbTab + vbTab, result.@key, vbCrLf)
			sb.AppendLine(vbTab + vbTab + "}")
			sb.Append(vbTab)
			sb.AppendLine("}")
			sb.AppendLine()
		Next

		Return sb.ToString()

	End Function
#>

Click the download images below to download the templates for both VB and C#. Until next time…

Happy Programming!