jQuery自动完成，MVC4和WebAPI

我从http://www.codeproject.com/Tips/639578/jQuery-Autocomplete-MVC-and-WebAPI下载了一个关于自动完成文本框的教程的源代码(例如开始键入，下拉框将出现与那些前几个字符匹配的选项)-我可以编译它，它工作得很好。

试图适应它的用户名查找，我有问题。一切都可以编译，但下拉菜单没有触发。我错过了什么，但我不知道是什么!

ApiController:

public class UserApiController : ApiController
{
    [HttpGet]
    public IEnumerable<ApplicationUser> GetUsers(string query = "")
    {
        using (var db = new ApplicationDbContext())
        {
            return String.IsNullOrEmpty(query) ? db.Users.ToList() :
            db.Users.Where(p => p.UserName.Contains(query)).ToList();
        }
    }
}

控制器:

    [HttpGet]
    public ActionResult Search()
    {
        return View();
    }
    [HttpPost]
    public ActionResult Search(ApplicationUser user)
    {
        return RedirectToAction("Details", "PrivateMessage", new { Id = user.Id });
    }
    public ActionResult Details(string Id)
    {
        using (var db = new ApplicationDbContext())
        {
            return View(db.Users.FirstOrDefault(p => p.Id == Id));
        }
    }

模型(这个古怪的名字是为了排除其他地方的冲突):

public class ComposeMyMessageModel
{
    public string Id { get; set; }
    public string Title { get; set; }
    public string NewAddress { get; set; }
}

Web页面:

@model MyWebsite.Models.ComposeMyMessageModel
<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/smoothness/jquery-ui.css" />
<script src="http://code.jquery.com/jquery-1.9.1.js"></script>
<script src="http://code.jquery.com/ui/1.10.3/jquery-ui.js"></script>
@{
  ViewBag.Title = "Compose";
}
@using (Html.BeginForm()){
  @Html.HiddenFor(model => model.Id)
  <input type="text" id="search" placeholder="Search for a product" required />
  <input type="submit" value="Go" id="submit" />
}
<script type="text/javascript">
    var url = '@Url.RouteUrl("DefaultApi", new { httproute = "", controller = "UserApi" })';
    $('#search').autocomplete({
        source: function (request, response) {
          $.ajax({
             url: url,
             data: { query: request.term },
             dataType: 'json',
             type: 'GET',
             success: function (data) {
                 response($.map(data, function (item) {
                     return {
                         label: item.Description,
                         value: item.Id
                     }
                 }));
             }
         })
     },
      select: function (event, ui) {
         $('#search').val(ui.item.label);
         $('#Id').val(ui.item.value);
         return false;
      },
     minLength: 1
   });
</script>  

路由:

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );
    }
}

如果我没有粘贴任何相关的代码，那是因为我不知道它是相关的!将相应更新。谢谢。