ActionResult with Javascript for a Ext.Store

ExtStoreResult.cs

using System.Web.Mvc;
using Newtonsoft.Json;

namespace ActionResults
{
    public class ExtStoreResult : ActionResult
    {
        public virtual string StoreName { get; set; }
        public virtual object StoreData { get; set; }

        // TODO: Use a decent template engine
        private const string extStoreTemplate = 
@"Ext.define('{0}', {{
    extend: 'Ext.data.Store',
    data: {1}
}});";

        public ExtStoreResult(string storeName, object storeData)
        {
            StoreName = storeName;
            StoreData = storeData;
        }

        public override void ExecuteResult(ControllerContext context)
        {
            var extStore = runTemplate(extStoreTemplate, StoreName, JsonConvert.SerializeObject(StoreData));
            var response = context.HttpContext.Response;
            response.ContentType = "text/javascript";
            response.Write(extStore);
        }

        private string runTemplate(string template, params object[] args)
        {
            return string.Format(template, args);
        }
    }
}