MVC 5 属性路由中添加自己的自定义约束

介绍约束

ASP.NET MVC和web api 同时支持简单和自定义约束，简单的约束看起来像：

routes.MapRoute("blog", "{year}/{month}/{day}",
    new { controller = "blog", action = "index" },
    new { year = @"d{4}", month = @"d{2}", day = @"d{2}" });

 属性路由约束简单版

 只匹配'temp/整数', 并且id>=1,id<=20

[Route("temp/{id:int:max(20):min(1)}]

 下面定义了默认支持的约束：

Constraint	Description	Example
alpha	Matches uppercase or lowercase Latin alphabet characters (a-z, A-Z)	{x:alpha}
bool	Matches a Boolean value.	{x:bool}
datetime	Matches a DateTime value.	{x:datetime}
decimal	Matches a decimal value.	{x:decimal}
double	Matches a 64-bit floating-point value.	{x:double}
float	Matches a 32-bit floating-point value.	{x:float}
guid	Matches a GUID value.	{x:guid}
int	Matches a 32-bit integer value.	{x:int}
length	Matches a string with the specified length or within a specified range of lengths.	{x:length(6)} {x:length(1,20)}
long	Matches a 64-bit integer value.	{x:long}
max	Matches an integer with a maximum value.	{x:max(10)}
maxlength	Matches a string with a maximum length.	{x:maxlength(10)}
min	Matches an integer with a minimum value.	{x:min(10)}
minlength	Matches a string with a minimum length.	{x:minlength(10)}
range	Matches an integer within a range of values.	{x:range(10,50)}
regex	Matches a regular expression.	{x:regex(^d{3}-d{3}-d{4}$)}

自定义路由约束

约束实现

public class LocaleRouteConstraint : IRouteConstraint
{
	public string Locale { get; private set; }
	public LocaleRouteConstraint(string locale)
	{
		Locale = locale;
	}
	public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
	{
		object value;
		if (values.TryGetValue("locale", out value) && !string.IsNullOrWhiteSpace(value as string))
		{
			string locale = value as string;
			if (isValid(locale))
			{
				return string.Equals(Locale, locale, StringComparison.OrdinalIgnoreCase);
			}
		}
		return false;
	}
	private bool isValid(string locale)
	{
		string[] validOptions = "EN-US|EN-GB|FR-FR".Split('|') ;
		return validOptions.Contains(locale.ToUpper());
	}
}

 增加自定义路由属性

public class LocaleRouteAttribute : RouteFactoryAttribute
{
	public LocaleRouteAttribute(string template, string locale)
		: base(template)
	{
		Locale = locale;
	}
	public string Locale
	{
		get;
		private set;
	}
	public override RouteValueDictionary Constraints
	{
		get
		{
			var constraints = new RouteValueDictionary();
			constraints.Add("locale", new LocaleRouteConstraint(Locale));
			return constraints;
		}
	}
	public override RouteValueDictionary Defaults
	{
		get
		{
			var defaults = new RouteValueDictionary();
			defaults.Add("locale", "en-us");
			return defaults;
		}
	}
}

 MVC Controller 或 Action使用自定义的约束属性

using System.Web.Mvc;
namespace StarDotOne.Controllers
{
    [LocaleRoute("hello/{locale}/{action=Index}", "EN-GB")]
    public class ENGBHomeController : Controller
    {
        // GET: /hello/en-gb/
        public ActionResult Index()
        {
            return Content("I am the EN-GB controller.");
        }
    }
}

 另一个controller

using System.Web.Mvc;
namespace StarDotOne.Controllers
{
    [LocaleRoute("hello/{locale}/{action=Index}", "FR-FR")]
    public class FRFRHomeController : Controller
    {
        // GET: /hello/fr-fr/
        public ActionResult Index()
        {
            return Content("Je suis le contrôleur FR-FR.");
        }
    }
}

'/hello/en-gb' 将会匹配到ENGBHomeController
’/hello/fr-fr'将会匹配到FRFRHomeController

这里还有另外一种方式：https://blogs.msdn.microsoft.com/webdev/2013/10/17/attribute-routing-in-asp-net-mvc-5/

 不用使用 attribute方式：

public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute(“{resource}.axd/{*pathInfo}”);
 
    var constraintsResolver = new DefaultInlineConstraintResolver();
 
    constraintsResolver.ConstraintMap.Add(“locale”, typeof(LocaleRouteConstraint));
 
    routes.MapMvcAttributeRoutes(constraintsResolver);
}

 controller代码是这样的

using System.Web.Mvc;
namespace StarDotOne.Controllers
{
    [Route("hello/{locale：locale(FR-FR)}/{action=Index}")]
    public class FRFRHomeController : Controller
    {
        // GET: /hello/fr-fr/
        public ActionResult Index()
        {
            return Content("Je suis le contrôleur FR-FR.");
        }
    }
}

应用场景可以自己定义。