第一个匹配路由必须同时指定控制器和操作？

Question

下面是我的代码：//inside UseMvc method:routes.MapRoute(   name: "NewRoute",   template: "/",   defaults: new { controller = "Home"});routes.MapRoute(   name: "default",    template: "{controller=Home}/{action=Index}/{id?}");我们知道路由系统只会找到第一个匹配的路由，所以第一个“NewRoute”应该在应用程序启动时匹配路由，因为它没有操作方法，所以我应该得到一个404错误页面，但是当我运行应用程序时，使用“默认”路由，显示正常页面。那么为什么路由系统一开始就没有选择“NewRoute”呢？

Answer 1

事实是NewRoute先检查，但路由找不到匹配的动作。然后它会匹配下一个路由规则。

Debug如果您启用日志记录级别appSettings.Development.json

{

"Logging": {

  "LogLevel": {

    "Default": "Debug",

    "System": "Information",

    "Microsoft": "Debug"

  }

}

}

并将启动CompatibilityVersion更改为2.1（asp.net core 2.2有另一种EndPoint机制）

services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

运行应用程序时，您可以在日志中看到整个过程：

dbug: Microsoft.AspNetCore.Routing.RouteBase[1]

      Request successfully matched the route with name 'NewRoute' and template '/'

dbug: Microsoft.AspNetCore.Mvc.Internal.ActionSelector[3]

      No actions matched the current request. Route values: controller=Home

dbug: Microsoft.AspNetCore.Mvc.Internal.MvcRouteHandler[3]

      No actions matched the current request. Route values: controller=Home

dbug: Microsoft.AspNetCore.Routing.RouteBase[1]

      Request successfully matched the route with name 'default' and template '{controller=Home}/{action=Index}/{id?}'

info: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker[3]

      Route matched with {action = "Index", controller = "Home"}. Executing controller action with signature Microsoft.AspNetCore.Mvc.IActionResult Index() on controller Core22MVC.Controllers.HomeController (Core22MVC).

匹配两次并选择default路线。