【Web API]无法添加AttributeRoutes的解决方案

1.按照微软官方文档，如果要使用AttributeRoutes，需要在APP_START里的WebApiConfig.cs的Register方法中添加一行：config.MapHttpAttributeRoutes();

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

            // Uncomment the following line of code to enable query support for actions with an IQueryable or IQueryable return type.
            // To avoid processing unexpected or malicious queries, use the validation settings on QueryableAttribute to validate incoming queries.
            // For more information, visit http://go.microsoft.com/fwlink/?LinkId=279712.
            //config.EnableQuerySupport();

            // To disable tracing in your application, please comment out or remove the following line of code
            // For more information, refer to: http://www.asp.net/web-api
            config.EnableSystemDiagnosticsTracing();
        }

但是我加了之后死命报错，划小红线，嘤嘤嘤

后来查到解决方法，是因为属性路由是WebAPI 2中才加的，需要将VS升级到WebAPI 2。在菜单栏Tools-->NuGet package manager--->package manager console,输入如下命令：

Install-Package Microsoft.AspNet.WebApi.WebHost

运行完毕，重启VS，小红线是不是神奇的消失啦，啦啦啦

2.升级之后会遇到一些问题，比如后来写代码运行的时候，又出问题了，报错信息如下：

'CommonServices.Areas.HelpPage.XmlDocumentationProvider' does not implement interface member 

解决方法，仍然是调出package manager console，运行如下命令：

install-package Microsoft.AspNet.WebApi.HelpPage

问题解决啦