ASP.NET MVC 3路径约束:非空的正则表达式

Question

我正在尝试创建一个路由约束但不确定什么是最好的.这是没有约束的路线:

context.MapRoute(
    "Accommodation_accomm_tags",
    "accomm/{controller}/{action}/{tag}",
    new { action = "Tags", controller = "AccommProperty" },
    new { tag = @"" } //Here I would like to put a RegEx for not null match
);

什么是最好的解决方案？

Answer 1

你能创建一个IRouteConstraint:

public class NotNullRouteConstraint : IRouteConstraint
{
  public bool Match(
    HttpContextBase httpContext, Route route, string parameterName, 
    RouteValueDictionary values, RouteDirection routeDirection)
  {
    return (values[parameterName] != null);
  }
}

你可以连线:

context.MapRoute(
  "Accommodation_accomm_tags",
  "accomm/{controller}/{action}/{tag}",
  new { action = "Tags", controller = "AccommProperty" },
  new { tag = new NotNullRouteConstraint() }
);

Answer 2

为什么你需要一个非空/空匹配的约束？通常,如果您定义这样的路线:

context.MapRoute(
    "Accommodation_accomm_tags",
    "accomm/{controller}/{action}/{tag}",
    new { action = "Tags", controller = "AccommProperty" },
);

并且tag未在请求URL中指定此路由根本不匹配.

如果您想要一个令牌是可选的,那么:

context.MapRoute(
    "Accommodation_accomm_tags",
    "accomm/{controller}/{action}/{tag}",
    new { action = "Tags", controller = "AccommProperty", tag = UrlParameter.Optional },
);

当您想要将给定路由令牌的值约束为某种特定格式时,将使用约束.