Lazy stuffs

MvcLazyActionResult.cs

    public class LazyActionResult : ActionResult
    {
        readonly Func<ActionResult> _innerResult;
        ActionResult _cachedResult;

        public LazyActionResult(Func<ActionResult> innerResult)
        {
            if (innerResult == null) throw new ArgumentNullException("innerResult");
            _innerResult = innerResult;
        }

        /// <summary>
        /// Enables processing of the result of an action method by a custom type that inherits from the <see cref="T:System.Web.Mvc.ActionResult"/> class.
        /// </summary>
        /// <param name="context">The context in which the result is executed. The context information includes the controller, HTTP content, request context, and route data.</param>
        public override void ExecuteResult(ControllerContext context)
        {
            InnerResult.ExecuteResult(context);
        }

        internal ActionResult InnerResult
        {
            get { return _cachedResult ?? (_cachedResult = _innerResult()); }
        }
    }

WebApiLazyFormatter.cs

    public class LazyUnwrapFormatter : MediaTypeFormatter
    {
        readonly MediaTypeFormatter _innerMediaTypeFormatter;

        public LazyUnwrapFormatter(MediaTypeFormatter innerMediaTypeFormatter)
        {
            _innerMediaTypeFormatter = innerMediaTypeFormatter;
        }

        public override bool CanReadType(Type type)
        {
            return true;
        }

        public override bool CanWriteType(Type type)
        {
            return true;
        }

        public override Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content, TransportContext transportContext)
        {
            var unwrappedValue = value;
            if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Lazy<>))
            {
                unwrappedValue = type.GetProperty("Value").GetValue(value, null);
            }

            return _innerMediaTypeFormatter.WriteToStreamAsync(type, unwrappedValue, writeStream, content, transportContext);
        }
    }