Serialize LLBLGEN Entity to json without LLBLGEN-specific fields

CommonEntityBaseExtensions.cs

using System.Collections.Generic;
using System.Dynamic;
using Newtonsoft.Json;
using Your.ORM.EntityClasses; // <- replace

namespace Your.Namespace // <-
{
	public static class CommonEntityBaseExtensions
	{
		/// <summary>
		/// Serializes EntityFields as json (and ignores other LLBLGEN-specific fields)
		/// </summary>
		public static string ToJson(this CommonEntityBase entity)
		{
			if (entity == null)
				return null;

			dynamic expando = new ExpandoObject();
			foreach (var field in entity.Fields)
			{
				((IDictionary<string, object>)expando).Add(field.Name, field.CurrentValue);
			}

			return JsonConvert.SerializeObject(expando);
		}
	}
}