根據路由值（命名空間）選擇ASP.NET Web API Controller

Question

我正在嘗試將各種Web API插件添加到我的MVC網站。 復制和粘貼API文件的DLL允許我使用默認路由調用適當的服務方法 - hostname / api / {controller} / {id}，但是當我有相同名稱但位於不同位置的控制器時，它會拋出錯誤（ DLL，命名空間）。 錯誤消息是這樣的（這是正常的）：

找到了多個匹配名為“Names”的控制器的類型。 如果為此請求提供服務的路由（'api / {controller} / {id}'）發現多個控制器定義了相同名稱但名稱不同的命名空間（不受支持），則會發生這種情況。 對'Names'的請求找到了以下匹配的控制器：ApiExt.NamesController ApiExt1.NamesController

我在不同的DLL（名稱空間）ApiExt，ApiExt1中有相同的“名稱”控制器。

我已經找到了一個類似的主題，根據API版本選擇控制器 - http://shazwazza.com/post/multiple-webapi-controllers-with-the-same-name-but-different-namespaces/ ，但這並不完全我需要的。 我需要根據路由值選擇控制器（命名空間），如下所示：

主機名/ API / {命名空間} / {控制器} / {ID}

我相信這絕對是可能的，但我不熟悉重寫MVC控制器選擇器（實現IHttpControllerSelector）。

有什么建議么？

謝謝。

Answer 1

你絕對可以做到這一點。 您需要通過實現IHttpControllerSelector來編寫自己的Controller Selector。 有關詳細的逐步說明，請參閱此鏈接。

Answer 2

描述解決方案的博客文章https://blogs.msdn.microsoft.com/webdev/2013/03/07/asp-net-web-api-using-namespaces-to-version-web-apis/ ，不包含完整的代碼，與過去提供的代碼有很糟糕的聯系。

這是一個提供Umbraco原創課程的blob

https://github.com/WebApiContrib/WebAPIContrib/blob/master/src/WebApiContrib/Selectors/NamespaceHttpControllerSelector.cs ，

完整列表，以防它被刪除：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Web.Http;
using System.Web.Http.Controllers;
using System.Web.Http.Dispatcher;

namespace WebApiContrib.Selectors
{
    //originally created for Umbraco https://github.com/umbraco/Umbraco-CMS/blob/7.2.0/src/Umbraco.Web/WebApi/NamespaceHttpControllerSelector.cs
    //adapted from there, does not recreate HttpControllerDescriptors, instead caches them
    public class NamespaceHttpControllerSelector : DefaultHttpControllerSelector
    {
        private const string ControllerKey = "controller";
        private readonly HttpConfiguration _configuration;
        private readonly Lazy<HashSet<NamespacedHttpControllerMetadata>> _duplicateControllerTypes;

        public NamespaceHttpControllerSelector(HttpConfiguration configuration)
            : base(configuration)
        {
            _configuration = configuration;
            _duplicateControllerTypes = new Lazy<HashSet<NamespacedHttpControllerMetadata>>(InitializeNamespacedHttpControllerMetadata);
        }

        public override HttpControllerDescriptor SelectController(HttpRequestMessage request)
        {
            var routeData = request.GetRouteData();
            if (routeData == null || routeData.Route == null || routeData.Route.DataTokens["Namespaces"] == null)
                return base.SelectController(request);

            // Look up controller in route data
            object controllerName;
            routeData.Values.TryGetValue(ControllerKey, out controllerName);
            var controllerNameAsString = controllerName as string;
            if (controllerNameAsString == null)
                return base.SelectController(request);

            //get the currently cached default controllers - this will not contain duplicate controllers found so if
            // this controller is found in the underlying cache we don't need to do anything
            var map = base.GetControllerMapping();
            if (map.ContainsKey(controllerNameAsString))
                return base.SelectController(request);

            //the cache does not contain this controller because it's most likely a duplicate, 
            // so we need to sort this out ourselves and we can only do that if the namespace token
            // is formatted correctly.
            var namespaces = routeData.Route.DataTokens["Namespaces"] as IEnumerable<string>;
            if (namespaces == null)
                return base.SelectController(request);

            //see if this is in our cache
            var found = _duplicateControllerTypes.Value.FirstOrDefault(x => string.Equals(x.ControllerName, controllerNameAsString, StringComparison.OrdinalIgnoreCase) && namespaces.Contains(x.ControllerNamespace));
            if (found == null)
                return base.SelectController(request);

            return found.Descriptor;
        }

        private HashSet<NamespacedHttpControllerMetadata> InitializeNamespacedHttpControllerMetadata()
        {
            var assembliesResolver = _configuration.Services.GetAssembliesResolver();
            var controllersResolver = _configuration.Services.GetHttpControllerTypeResolver();
            var controllerTypes = controllersResolver.GetControllerTypes(assembliesResolver);

            var groupedByName = controllerTypes.GroupBy(
                t => t.Name.Substring(0, t.Name.Length - ControllerSuffix.Length),
                StringComparer.OrdinalIgnoreCase).Where(x => x.Count() > 1);

            var duplicateControllers = groupedByName.ToDictionary(
                g => g.Key,
                g => g.ToLookup(t => t.Namespace ?? String.Empty, StringComparer.OrdinalIgnoreCase),
                StringComparer.OrdinalIgnoreCase);

            var result = new HashSet<NamespacedHttpControllerMetadata>();

            foreach (var controllerTypeGroup in duplicateControllers)
            {
                foreach (var controllerType in controllerTypeGroup.Value.SelectMany(controllerTypesGrouping => controllerTypesGrouping))
                {
                    result.Add(new NamespacedHttpControllerMetadata(controllerTypeGroup.Key, controllerType.Namespace,
                        new HttpControllerDescriptor(_configuration, controllerTypeGroup.Key, controllerType)));
                }
            }

            return result;
        }

        private class NamespacedHttpControllerMetadata
        {
            private readonly string _controllerName;
            private readonly string _controllerNamespace;
            private readonly HttpControllerDescriptor _descriptor;

            public NamespacedHttpControllerMetadata(string controllerName, string controllerNamespace, HttpControllerDescriptor descriptor)
            {
                _controllerName = controllerName;
                _controllerNamespace = controllerNamespace;
                _descriptor = descriptor;
            }

            public string ControllerName
            {
                get { return _controllerName; }
            }

            public string ControllerNamespace
            {
                get { return _controllerNamespace; }
            }

            public HttpControllerDescriptor Descriptor
            {
                get { return _descriptor; }
            }
        }
    }
}

然后只需將Namespaces標記添加到路由中

route.DataTokens["Namespaces"] = new string[] {"Foo.Controllers"};

它還可以通過緩存實現更多生產。