带有区域的WebAPI路由-缺少可选参数时出现404错误

Question

当我尝试不带可选参数的WebAPI控制器时遇到了404错误。我尝试将Global.asax.cs中的路线初始化命令重新排序无济于事。WebAPI在一个区域中，因此我注释掉该区域的路由信息​​，因此找不到该路由。这是我所拥有的：

在WebApiConfig.cs中：

        public static void Register(HttpConfiguration configuration)
    {
        configuration.Routes.MapHttpRoute("DefaultAPI",
            "API/{controller}/{action}/{id}",
            new { id = RouteParameter.Optional });

        // From http://weblogs.asp.net/fbouma/how-to-make-asp-net-webapi-serialize-your-llblgen-pro-entities-to-json
        var json = configuration.Formatters.JsonFormatter;
        json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects;
        json.SerializerSettings.ContractResolver = new DefaultContractResolver()
        {
            IgnoreSerializableInterface = true,
            IgnoreSerializableAttribute = true
        };

        var appXmlType = configuration.Formatters.XmlFormatter.SupportedMediaTypes.FirstOrDefault(t => t.MediaType == "application/xml");
        configuration.Formatters.XmlFormatter.SupportedMediaTypes.Remove(appXmlType);
    }

在APIAreaRegistration.cs中：

        public override void RegisterArea(AreaRegistrationContext context)
    {
        //context.MapRoute(
        //    "API_default",
        //    "API/{controller}/{action}/{id}",
        //    new { action = "Index", id = UrlParameter.Optional }
        //);
    }

在Global.asax.cs中：

        protected void Application_Start()
    {
        AreaRegistration.RegisterAllAreas();
        GlobalConfiguration.Configure(WebApiConfig.Register); 
        //WebApiConfig.Register(GlobalConfiguration.Configuration); 
        WebApiConfig.RegisterSiteMap();

        RouteConfig.RegisterRoutes(RouteTable.Routes);
    }

（请注意：我尝试使用注释行与其上方的行，没有区别）

这是我有问题的控制器：

        [HttpGet]
    public IEnumerable<LocationFilterViewModel> GetLocations(int? id)
    {
        LocationFilterCollection Locations = LocationFilterCollection.GetLocations(id.HasValue ? id.Value : 0);
        List<LocationFilterViewModel> myList = new List<LocationFilterViewModel>();
        foreach (LocationFilterEntity myEntity in Locations)
        {
            LocationFilterViewModel myModel = new LocationFilterViewModel();
            InitializeModel(myEntity, myModel);
            myList.Add(myModel);
        }
        return myList;
    }

最后，这是我的查看代码：

@Html.Kendo().TreeView().Name("Locations").LoadOnDemand(false).DataTextField("LocationName").DragAndDrop(false).Checkboxes(true).AutoBind(true).ExpandAll(true).DataSource(dataSource => dataSource
.Model(model => model
.Id("LocationId")
.HasChildren("HasChildren"))
.Read(read => read.Url(@Url.HttpRouteUrl("DefaultAPI", new { controller="LocationFilterAPI", action="GetLocations" }))))

如果我在action =语句后添加id = 0，它将不再返回404错误，而是继续返回0节点，而不是返回当前节点的子节点。如果我省略id = 0，它将返回404错误，即

/ API / LocationFilterAPI / GetLocations / 0-正常工作

/ API / LocationFilterAPI / GetLocations-返回404

我在此控制器中进行的所有其他API调用都具有必需参数或根本没有参数，并且所有这些都工作正常。我整个下午都在撞头。任何见识将不胜感激。

谢谢！

劳里

ps为了回应评论，下面是我的RegisterRoutes方法：

        public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapRoute(
            name: "LibraryCategoryList",
            url: "Library/List/{id}/{id2}",
            defaults: new { controller = "Library", action = "List", id = UrlParameter.Optional,id2=UrlParameter.Optional }
            );
        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional },
            namespaces: new[] { "BFRDP.Controllers" }
        );
    }

Answer 1

尝试为您的方法参数分配null indicating that is optional

public IEnumerable<LocationFilterViewModel> GetLocations(int? id = null)