WCF Web Api with generic get method

WCFWebApiGenericSample.cs

using System.Linq;
using System.Net;
using System.ServiceModel;
using System.ServiceModel.Web;
using ContactManager.Infrastructure;
using ContactManager.Repositories;
using ContactManager.Resources;
using Microsoft.ApplicationServer.Http.Dispatcher;

namespace ContactManager.APIs
{
    [ServiceContract]
    public interface IBaseApi<T> where T : Entity
    {
        [WebGet]
        IQueryable<T> Get();
    }

    public abstract class BaseApi<T> : IBaseApi<T> where T : Entity
    {
        protected IRepository<T> repository;

        public IQueryable<T> Get()
        {
            return repository.FindAll().AsQueryable();
        }
    }


    public class PeoplesApi : BaseApi<People>
    {
        public PeoplesApi()
        {
            repository = new PeopleRepository();
        }
    }

    public class ContactsApi : BaseApi<Contact>
    {
        public ContactsApi()
        {
            repository = new ContactRepository();
        }

        [WebGet(UriTemplate = "{id}")]
        public Contact GetItem(int id)
        {
            var contact = repository.Find(id);
            contact.AssertIsNotNull();
            return contact;
        }

        [WebInvoke]
        public Contact Post(Contact contact)
        {
            repository.Add(contact);
            return contact;
        }

        [WebInvoke(UriTemplate = "{id}")]
        public Contact Put(Contact contact, int id)
        {
            var existingContact = repository.Find(id);
            existingContact.AssertIsNotNull();
            existingContact.Name = contact.Name;
            return existingContact;
        }

        [WebInvoke(UriTemplate = "{id}")]
        public Contact Delete(int id)
        {
            var contact = repository.Find(id);
            contact.AssertIsNotNull();
            repository.Remove(id);
            return contact;
        }
    }

    public static class WebExtentions
    {
        public static void AssertIsNotNull<T>(this T value) where T : Entity
        {
            if (value == null)
                throw new HttpResponseException(HttpStatusCode.NotFound);
        }
    }
}