InventoryTracker/InventoryTraker.Web/ActionResults/BetterJsonResult.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using InventoryTraker.Web.Utilities;

namespace InventoryTraker.Web.ActionResults
{
	public class BetterJsonResult : JsonResult
	{
		public IList<string> ErrorMessages { get; }

		public BetterJsonResult()
		{
			ErrorMessages = new List<string>();
		}

		public void AddError(string errorMessage)
		{
			ErrorMessages.Add(errorMessage);
		}

		public static BetterJsonResult Error(string errorMessage)
		{
			var betterJsonResult = new BetterJsonResult();
			betterJsonResult.AddError(errorMessage);
			return betterJsonResult;
		}

		public override void ExecuteResult(ControllerContext context)
		{
			DoUninterestingBaseClassStuff(context);

			SerializeData(context.HttpContext.Response);
		}

		private void DoUninterestingBaseClassStuff(ControllerContext context)
		{
			if (context == null)
			{
				throw new ArgumentNullException("context");
			}

			if (JsonRequestBehavior == JsonRequestBehavior.DenyGet &&
			    "GET".Equals(context.HttpContext.Request.HttpMethod, StringComparison.OrdinalIgnoreCase))
			{
				throw new InvalidOperationException(
					"GET access is not allowed.  Change the JsonRequestBehavior if you need GET access.");
			}

			var response = context.HttpContext.Response;
			response.ContentType = string.IsNullOrEmpty(ContentType) ? "application/json" : ContentType;

			if (ContentEncoding != null)
			{
				response.ContentEncoding = ContentEncoding;
			}
		}

		protected virtual void SerializeData(HttpResponseBase response)
		{
			if (ErrorMessages.Any())
			{
				Data = new
				{
					ErrorMessage = string.Join("\n", ErrorMessages),
					ErrorMessages = ErrorMessages.ToArray()
				};

				response.StatusCode = 400;
			}

			if (Data == null) return;

			response.Write(Data.ToJson());
		}
	}

	public class BetterJsonResult<T> : BetterJsonResult
	{
		public new T Data
		{
			get { return (T)base.Data; }
			set { base.Data = value; }
		}
	}
}