RebaseODataLinks.cs

using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Net.Http.Headers;
using System.ServiceModel;
using System.Threading;
using System.Threading.Tasks;
using System.Web.Http;
using System.Web.Http.Controllers;
using System.Web.Http.OData;
using System.Web.Http.OData.Builder;
using System.Web.Http.Routing;
using System.Web.Http.SelfHost;

namespace RebaseODataLinks
{
    class Program
    {
        static void Main(string[] args)
        {
            ODataConventionModelBuilder builder = new ODataConventionModelBuilder();
            builder.EntitySet<Customer>("Customers");
            builder.EntitySet<Order>("Orders");

            HttpSelfHostConfiguration config = new HttpSelfHostConfiguration("http://localhost:8080");
            config.HostNameComparisonMode = HostNameComparisonMode.Exact;

            HttpSelfHostServer server = new HttpSelfHostServer(config);
            server.Configuration.Routes.MapODataRoute("odata", "", builder.GetEdmModel());

            // inject the custom message handler that replaces urlhelper.
            server.Configuration.MessageHandlers.Add(new LinkRewritingMessageHandler());

            server.OpenAsync().Wait();

            HttpClient client = new HttpClient();
            var request = new HttpRequestMessage(HttpMethod.Get, "http://localhost:8080/Customers");
            request.Headers.Accept.Add(MediaTypeWithQualityHeaderValue.Parse("application/json;odata=fullmetadata"));
            var response = client.SendAsync(request).Result;

            Console.WriteLine(response);
            Console.WriteLine(response.Content.ReadAsStringAsync().Result);
        }
    }

    // A message handler to inject the custom url helper.
    public class LinkRewritingMessageHandler : DelegatingHandler
    {
        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            HttpResponseMessage response = await base.SendAsync(request, cancellationToken);

            // replace only for OData requests.
            if (request.GetEdmModel() != null)
            {
                HttpRequestContext requestContext = request.GetRequestContext();
                requestContext.Url = new RewritingUrlHelper(request);
            }

            return response;
        }
    }

    // A custom url helper that rewrites links
    public class RewritingUrlHelper : UrlHelper
    {
        Uri _baseUri = new Uri("http://odata.org");

        public RewritingUrlHelper(HttpRequestMessage request)
            : base(request)
        {
        }

        // This method is called for each and every link that we generate using OData.
        public override string Link(string routeName, IDictionary<string, object> routeValues)
        {
            string url = base.Link(routeName, routeValues);

            // rebase to the baseUri.
            return new Uri(_baseUri, new Uri(url).PathAndQuery).AbsoluteUri;
        }
    }

    #region Models

    public class Customer
    {
        public int ID { get; set; }

        public IEnumerable<Order> Orders { get; set; }
    }

    public class Order
    {
        public int ID { get; set; }
    }

    public class CustomersController : ODataController
    {
        public Customer Get()
        {
            return new Customer();
        }
    }

    #endregion
}