Fat Agnus

/// <summary>
/// A base controller that will enable you to serve your data in either Json, Xml, Html
/// </summary>
public abstract class FormatController : Controller
{
	/// <summary>
	/// The Key to extract the format from Route Data
	/// </summary>
	private const string FORMAT_KEY = "Format";
 
	/// <summary>
	/// The type of files we can server the requested content in
	/// </summary>
	public enum FileFormat { Html, Json, Xml }
 
	protected FormatController()
	{
		// Our Default format
		RequestedFormat = FileFormat.Html;
	}
 
	/// <summary>
	/// The format that has been requested
	/// </summary>
	protected FileFormat RequestedFormat { get; private set; }
 
	/// <summary>
	/// Occurs before an action is executed
	/// </summary>
	/// <param name="filterContext"></param>
	protected override void OnActionExecuting(ActionExecutingContext filterContext)
	{
		base.OnActionExecuting(filterContext);
 
		var routeValues = filterContext.RouteData.Values;
		if (routeValues.ContainsKey(FORMAT_KEY))
		{
			var requestedFormat = routeValues[FORMAT_KEY].ToString();
			if (IsValidFormat(requestedFormat))
			{
				RequestedFormat = (FileFormat)Enum.Parse(typeof(FileFormat), requestedFormat, true);
			}
		}
	}
 
	/// <summary>
	/// Verifies that the requested format is one that can be servered
	/// </summary>
	/// <param name="requestedFormat"></param>
	/// <returns></returns>
	private bool IsValidFormat(string requestedFormat)
	{
		return Enum.GetNames(typeof(FileFormat)).Any(format => format.ToLower() == requestedFormat.ToLower());
	}
 
	/// <summary>
	/// Returns the content in the requested format
	/// </summary>
	/// <param name="viewModel">Viewmodel</param>
	/// <returns>ActionResult</returns>
	protected ActionResult FormatView(object viewModel)
	{
		switch (RequestedFormat)
		{
			case FileFormat.Html:
				return View(viewModel);
			case FileFormat.Json:
				return Json(viewModel);
			case FileFormat.Xml:
				return new XmlResult(viewModel);
			default:
				throw new FormatException(string.Concat("Cannot server the content in the request format: ", RequestedFormat));
		}
	}
}

public class Pizza
{
	public int Number { get; set; }
	public string Name { get; set; }
	public string Price { get; set; }
}
 
public class HomeController : FormatController
{
	public ActionResult Index()
	{
		var pizzas = new[]
			{
				new Pizza {Number = 1, Name = "Pizza 1", Price = "$10"},
				new Pizza {Number = 2, Name = "Pizza 2", Price = "$13"},
				new Pizza {Number = 3, Name = "Pizza 3", Price = "$20"}
			};
 
		return FormatView(pizzas);
	}
}

// Add this to Global.asax
routes.MapRoute(
	"Format",
	"{controller}/{action}.{format}/{id}",
	new {id = ""}
);