Helps with custom "deep routes" within ASP.NET MVC of the form "parent/{parentId}/child/{childId}/deeperChild/{id}" by examining route data and inserting the values into properties or fields that match within the controller.

ExampleController.cs

[RoutePrefix("Parent/{parentId:int}/ChildThings")]
[InjectRouteData]
public class ExampleController : Controller
{
	private int _parentId;
	private ParentThing parentThing;
	
	// Value is injected from the route by the InjectRouteDataAttribute and sets parentThing.
	protected int parentId
	{
		get { return this._parentId; }
		set
		{
			this._parentId = value;
			this.parentThing = // Some expression to retrieve parentThing by its id
		}
	}
	
	[Route("")]
	public ActionResult Index()
	{
		// Able to use parentId or parentThing from any action method
		return View();
	}

	[Route("{id:int}")]
	public ActionResult Details(int id)
	{
		return View();
	}
	
	[Route("Edit/{id:int}")]
	public ActionResult Edit(int id)
	{
		return View();
	}
	
	// etc.
}

InjectRouteDataAttribute.cs

public class InjectRouteDataAttribute : ActionFilterAttribute
{
	// Dictionary to hold all of the reflected PropertyInfos and MemberInfos
	private static Dictionary<Type, Dictionary<string, MemberInfo>> controllerReflectionInfo
		= new Dictionary<Type, Dictionary<string, MemberInfo>>();

	public override void OnActionExecuting(ActionExecutingContext filterContext)
	{
		base.OnActionExecuting(filterContext);

		// Get the reflection info for this controller type
		Dictionary<string, MemberInfo> controllerFields = GetControllerFields(filterContext.Controller.GetType());

		// Loop through route data values looking for reflected properties/fields that match on name
		var routeData = filterContext.RouteData.Values;
		foreach (string key in routeData.Keys)
		{
			MemberInfo member = null;
			if (controllerFields.TryGetValue(key, out member))
			{
				if (member is PropertyInfo)
				{
					var pi = member as PropertyInfo;
					object value = Convert.ChangeType(routeData[key], pi.PropertyType);
					pi.SetValue(filterContext.Controller, value);
				}
				else if (member is FieldInfo)
				{
					var fi = member as FieldInfo;
					object value = Convert.ChangeType(routeData[key], fi.FieldType);
					fi.SetValue(filterContext.Controller, value);
				}
			}
		}
	}

	private Dictionary<string, MemberInfo> GetControllerFields(Type type)
	{
		Dictionary<string, MemberInfo> result = null;

		// Standard check/lock/check pattern to avoid race conditions
		if (!controllerReflectionInfo.TryGetValue(type, out result))
		{
			lock (controllerReflectionInfo)
			{
				if (!controllerReflectionInfo.TryGetValue(type, out result))
				{
					result = BuildControllerFields(type);
					controllerReflectionInfo[type] = result;
				}
			}
		}

		return result;
	}

	private Dictionary<string, MemberInfo> BuildControllerFields(Type type)
	{
		const BindingFlags flags = BindingFlags.SetField
			                        | BindingFlags.SetProperty
			                        | BindingFlags.Public
			                        | BindingFlags.NonPublic
			                        | BindingFlags.Instance
			                        | BindingFlags.DeclaredOnly;

		var results = new Dictionary<string, MemberInfo>();

		// We don't want properties and fields from all the way down in the MVC framework,
		// so start at the current controller type and loop through base types until
		// we leave the top-level controller's assembly.
		for (var reflectType = type; reflectType.Assembly == type.Assembly; reflectType = reflectType.BaseType)
		{
			var fieldsAndProperties = type.GetMembers(flags)
				.Where(mi => mi is FieldInfo || mi is PropertyInfo)
				// If something is overridden in a higher-level class we don't want it
				// replaced by the base class version
				.Where(mi => !results.ContainsKey(mi.Name));

			// Add each item found to the result dictionary
			foreach (var member in fieldsAndProperties)
				results.Add(member.Name, member);
		}

		return results;
	}
}

Hey, this was a useful bit of code, just wanted to put out that the call to type.GetMembers in BuildControllerFields should be reflectType.GetMembers, I think …