asp.net-mvc - 有没有办法让 RoutePrefix 以可选参数开头？

Question

我想通过以下 URL 访问 Bikes Controller :

/bikes     // (default path for US)
/ca/bikes  // (path for Canada)

实现这一目标的一种方法是每个操作使用多个路由属性:

[Route("bikes")]
[Route("{country}/bikes")]
public ActionResult Index()

为了保持干燥，我更愿意使用 RoutePrefix，但不允许使用多个路由前缀:

[RoutePrefix("bikes")]
[RoutePrefix("{country}/bikes")] // <-- Error: Duplicate 'RoutePrefix' attribute    
public class BikesController : BaseController

    [Route("")]
    public ActionResult Index()

我尝试过仅使用此路由前缀:

[RoutePrefix("{country}/bikes")]
public class BikesController : BaseController

结果:/ca/bikes 有效，/bikes 404s。

我尝试将国家/地区设为可选:

[RoutePrefix("{country?}/bikes")]
public class BikesController : BaseController

相同的结果:/ca/bikes 有效，/bikes 404s。

我尝试为国家/地区提供默认值:

[RoutePrefix("{country=us}/bikes")]
public class BikesController : BaseController

相同的结果:/ca/bikes 有效，/bikes 404s。

是否有其他方法可以使用属性路由来实现我的目标？(是的，我知道我可以通过在 RouteConfig.cs 中注册路由来完成这些工作，但这不是我在这里寻找的)。

我正在使用 Microsoft.AspNet.Mvc 5.2.2。

仅供引用:这些是简化的示例 - 实际代码具有针对 {country} 值的 IRouteConstraint，例如:

[Route("{country:countrycode}/bikes")]

Answer 1

我参加聚会有点晚了，但我有一个解决这个问题的可行解决方案。请查看我关于此问题的详细博客文章 here

我正在下面写下摘要

您需要创建如下所示的 2 个文件

• _3bTechTalkMultiplePrefixDirectRouteProvider.cs

    using System;
    using System.Collections.Generic;
    using System.Collections.ObjectModel;
    using System.Web.Http.Controllers;
    using System.Web.Http.Routing;

    namespace _3bTechTalk.MultipleRoutePrefixAttributes {
     public class _3bTechTalkMultiplePrefixDirectRouteProvider: DefaultDirectRouteProvider {
      protected override IReadOnlyList  GetActionDirectRoutes(HttpActionDescriptor actionDescriptor, IReadOnlyList  factories, IInlineConstraintResolver constraintResolver) {
       return CreateRouteEntries(GetRoutePrefixes(actionDescriptor.ControllerDescriptor), factories, new [] {
        actionDescriptor
       }, constraintResolver, true);
      }

      protected override IReadOnlyList  GetControllerDirectRoutes(HttpControllerDescriptor controllerDescriptor, IReadOnlyList  actionDescriptors, IReadOnlyList  factories, IInlineConstraintResolver constraintResolver) {
       return CreateRouteEntries(GetRoutePrefixes(controllerDescriptor), factories, actionDescriptors, constraintResolver, false);
      }

      private IEnumerable  GetRoutePrefixes(HttpControllerDescriptor controllerDescriptor) {
       Collection  attributes = controllerDescriptor.GetCustomAttributes  (false);
       if (attributes == null)
        return new string[] {
         null
        };

       var prefixes = new List  ();
       foreach(var attribute in attributes) {
        if (attribute == null)
         continue;

        string prefix = attribute.Prefix;
        if (prefix == null)
         throw new InvalidOperationException("Prefix can not be null. Controller: " + controllerDescriptor.ControllerType.FullName);
        if (prefix.EndsWith("/", StringComparison.Ordinal))
         throw new InvalidOperationException("Invalid prefix" + prefix + " in " + controllerDescriptor.ControllerName);

        prefixes.Add(prefix);
       }

       if (prefixes.Count == 0)
        prefixes.Add(null);

       return prefixes;
      }


      private IReadOnlyList  CreateRouteEntries(IEnumerable  prefixes, IReadOnlyCollection  factories, IReadOnlyCollection  actions, IInlineConstraintResolver constraintResolver, bool targetIsAction) {
       var entries = new List  ();

       foreach(var prefix in prefixes) {
        foreach(IDirectRouteFactory factory in factories) {
         RouteEntry entry = CreateRouteEntry(prefix, factory, actions, constraintResolver, targetIsAction);
         entries.Add(entry);
        }
       }

       return entries;
      }


      private static RouteEntry CreateRouteEntry(string prefix, IDirectRouteFactory factory, IReadOnlyCollection  actions, IInlineConstraintResolver constraintResolver, bool targetIsAction) {
       DirectRouteFactoryContext context = new DirectRouteFactoryContext(prefix, actions, constraintResolver, targetIsAction);
       RouteEntry entry = factory.CreateRoute(context);
       ValidateRouteEntry(entry);

       return entry;
      }


      private static void ValidateRouteEntry(RouteEntry routeEntry) {
       if (routeEntry == null)
        throw new ArgumentNullException("routeEntry");

       var route = routeEntry.Route;
       if (route.Handler != null)
        throw new InvalidOperationException("Direct route handler is not supported");
      }
     }
    }

• 3bTechTalkRoutePrefix.cs

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Web;
    using System.Web.Http;

    namespace _3bTechTalk.MultipleRoutePrefixAttributes
    {
        [AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
        public class _3bTechTalkRoutePrefix : RoutePrefixAttribute
        {
            public int Order { get; set; }

            public _3bTechTalkRoutePrefix(string prefix) : this(prefix, 0) { }

            public _3bTechTalkRoutePrefix(string prefix, int order) : base(prefix)
            {
                Order = order;
            }        
        }
    }

完成后，打开WebApiConfig.cs并将其添加到给定行下方

config.MapHttpAttributeRoutes(new _3bTechTalkMultiplePrefixDirectRouteProvider());

就是这样，现在您可以在 controller 中添加多个路由前缀。下面的例子

    [_3bTechTalkRoutePrefix("api/Car", Order = 1)]
    [_3bTechTalkRoutePrefix("{CountryCode}/api/Car", Order = 2)]
    public class CarController: ApiController {
     [Route("Get")]
     public IHttpActionResult Get() {
      return Ok(new {
       Id = 1, Name = "Honda Accord"
      });
     }
    }

我已经上传了一个工作解决方案 here

快乐编码:)