C# ASP.NET路由-仅当为数字时添加路由？

我正在尝试使用ASP.NET路由生成路由，但我只希望在某些值为数字时应用它

        // Routing for Archive Pages
        routes.Add("Category1Archive", new Route("{CategoryOne}/{Year}/{Month}", new CategoryAndPostHandler()));
        routes.Add("Category2Archive", new Route("{CategoryOne}/{CategoryTwo}/{Year}/{Month}", new CategoryAndPostHandler()));

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有没有办法知道{Year}和{Month}是否是数值。否则，此路由与其他路由冲突。

您可以使用以下方法实现所需的筛选器：

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Richard是对的，但我想补充一点：

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好的，谢谢理查德和马丁为我指明了正确的方向。我最终需要的语法是：

routes.Add("Category1Archive", new Route("{CategoryOne}/{Year}/{Month}/", new CategoryAndPostHandler()) { Constraints = new RouteValueDictionary(new { Year = @"^\d+$", Month = @"^\d+$" }) });
routes.Add("Category2Archive", new Route("{CategoryOne}/{CategoryTwo}/{Year}/{Month}/", new CategoryAndPostHandler()) { Constraints = new RouteValueDictionary(new { Year = @"^\d+$", Month = @"^\d+$" }) });

routes.Add("Category1Archive", new Route("{CategoryOne}/{Year}/{Month}/", new CategoryAndPostHandler()) { Constraints = new RouteValueDictionary(new { Year = @"^\d+$", Month = @"^\d+$" }) });
routes.Add("Category2Archive", new Route("{CategoryOne}/{CategoryTwo}/{Year}/{Month}/", new CategoryAndPostHandler()) { Constraints = new RouteValueDictionary(new { Year = @"^\d+$", Month = @"^\d+$" }) });