dynamic - 如何在*Application_Start之后动态添加OData Web Api路由？

Question

我有一个应用程序，需要动态添加 OData 路由。我可以在 Application_Start 之后添加常规路由，但使用OData路由时遇到困难。

以下是我尝试动态添加 OData Web Api 路由的方法。在我的 WebApiConfig 中，我添加了一个产品路由:

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        var builder = new ODataConventionModelBuilder();
        builder.EntitySet<Product>("Products");
        config.MapODataServiceRoute(routeName: "ProductsRoute", routePrefix: "odata", model: builder.GetEdmModel());
    }
}

然后在我的 ProductsController 中，我在 Products GET 方法中添加以下调用，当我转到 http:///odata/Products 时成功调用该调用(是的，有点奇怪，但这是演示添加Application_Start 之后的路线):

GlobalConfiguration.Configure(WebApiConfig.AddOrderRoute);

WebApiConfig.AddOrderRoute 方法被正确调用并执行，没有错误:

public static void AddOrderRoute(HttpConfiguration config)
{
    var builder = new ODataConventionModelBuilder();
    builder.EntitySet<Order>("Orders");
    config.MapODataServiceRoute(routeName: "OrdersRoute", routePrefix: "odata", model: builder.GetEdmModel());
    config.EnsureInitialized();
}

所以您可能认为现在我已经正确配置了订单路由。但是当我访问 http:///odata/Orders 时，出现以下错误:

ExceptionMessage=The object has not yet been initialized. 
Ensure that HttpConfiguration.EnsureInitialized() is called in the 
application's startup code after all other initialization code.

StackTrace=   at System.Web.OData.Routing.Conventions.AttributeRoutingConvention.get_AttributeMappings()
   at System.Web.OData.Routing.Conventions.AttributeRoutingConvention.SelectController(ODataPath odataPath, HttpRequestMessage request)
   at System.Web.OData.Routing.ODataPathRouteConstraint.SelectControllerName(ODataPath path, HttpRequestMessage request)
   at System.Web.OData.Routing.ODataPathRouteConstraint.Match(HttpRequestMessage request, IHttpRoute route, String parameterName, IDictionary`2 values, HttpRouteDirection routeDirection)
   at System.Web.Http.Routing.HttpRoute.ProcessConstraint(HttpRequestMessage request, Object constraint, String parameterName, HttpRouteValueDictionary values, HttpRouteDirection routeDirection)
   at System.Web.Http.Routing.HttpRoute.ProcessConstraints(HttpRequestMessage request, HttpRouteValueDictionary values, HttpRouteDirection routeDirection)
   at System.Web.Http.Routing.HttpRoute.GetRouteData(String virtualPathRoot, HttpRequestMessage request)
   at System.Web.Http.WebHost.Routing.HttpWebRoute.GetRouteData(HttpContextBase httpContext)

请注意，我正在 AddOrderRoute 中调用 config.EnsureInitialized()。

我错过了什么？

注意:如果我在 WebApiConfig.Register() 方法末尾调用 AddOrderRoute，则我的订单路由可用且正在工作，因此我知道我的订单实体、上下文和 Controller 工作正常。只有当我在应用程序初始化完成后调用它时，我才会遇到问题。

Answer 1

嗯，我花了一些时间与 MSDN 上的好心人交流并得到了答案!

以下是需要注册 Orders 实体路由的方式:

var builder = new ODataConventionModelBuilder();
builder.EntitySet<Order>("Orders");

var route = config.Routes.Where(r => r is System.Web.OData.Routing.ODataRoute).First();
var odataRoute = route as System.Web.OData.Routing.ODataRoute;

config.MapODataServiceRoute(
    routeName: "OrdersRoute", 
    routePrefix: "odata", 
    model: builder.GetEdmModel(),
    pathHandler: odataRoute.PathRouteConstraint.PathHandler,
    routingConventions: odataRoute.PathRouteConstraint.RoutingConventions);

不错。现在.../odata/Orders 可以正常访问了。