PaginableResultActionFilter.cs

    using System;
    using System.Linq;
    using System.Net.Http;
    using System.Web.Http.Filters;
    using Newtonsoft.Json;
    using PaginableCollections;

    public class PaginableResultActionFilter : ActionFilterAttribute
    {
        public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
        {
            if (actionExecutedContext.Response == null || !actionExecutedContext.Response.IsSuccessStatusCode)
                return;

            IPaginable paginable;

            if (actionExecutedContext.Response.TryGetContentValue<IPaginable>(out paginable))
            {
                actionExecutedContext.Response.Headers.Add(
                    "X-Paginable",
                    JsonConvert.SerializeObject(
                        new PaginationHeader(paginable), 
                        actionExecutedContext.ActionContext.ControllerContext.Configuration.Formatters.JsonFormatter.SerializerSettings));
            }
        }


        public class PaginationHeader
        {
            public PaginationHeader(IPaginable paginable)
            {
                this.PageNumber = paginable.PageNumber;
                this.ItemCountPerPage = paginable.ItemCountPerPage;
                this.TotalItemCount = paginable.TotalItemCount;
                this.TotalPageCount = paginable.TotalPageCount;
            }

            public int ItemCountPerPage { get; set; }

            public int PageNumber { get; set; }

            public int TotalItemCount { get; set; }

            public int TotalPageCount { get; set; }
        }
    }