C# 用 Lambda 設定 MVC Route Constraint

MVC 的 Route Constraint 支援 Regular Pattern (string) 以及 IRouteConstraint，簡單的限制還可以用 Regular 處理，複雜的就需要實作 IRouteConstraint 了，既然都是一次工，索性就想要搭配 Lambda 讓設定可以更彈性的點。

原始碼

1. routes.MapRoute( 
2.    name: "Default", 
3.    url: "{controller}/{action}/{id}", 
4.    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }, 
5.    constraints: new { controller = new ValueConstraint(x => x.ToUpper() != "WCF") } 
6. ); 

routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional },
    constraints: new { controller = new ValueConstraint(x => x.ToUpper() != "WCF") }
);

原始碼

1. public class ValueConstraint : IRouteConstraint 
2. { 
3.    private Func<string, bool> _match; 
4.  
5.    public ValueConstraint(Func<string, bool> match) 
6.    { 
7.        _match = match; 
8.    } 
9.  
10.    public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection) 
11.    { 
12.        return _match("" + values[parameterName]); 
13.    } 
14. } 

public class ValueConstraint : IRouteConstraint
{
    private Func<string, bool> _match;

    public ValueConstraint(Func<string, bool> match)
    {
        _match = match;
    }

    public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
    {
        return _match("" + values[parameterName]);
    }
}

順便增加了 HttpContextBase 的處理

原始碼

1. routes.MapRoute( 
2.    name: "Default", 
3.    url: "{controller}/{action}/{id}", 
4.    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }, 
5.    constraints: new { authenticated = new HttpConstraint(x => x.Request.IsAuthenticated) } 
6. ); 

routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional },
    constraints: new { authenticated = new HttpConstraint(x => x.Request.IsAuthenticated) }
);

原始碼

1. public class HttpConstraint : IRouteConstraint 
2. { 
3.    private Func<HttpContextBase, bool> _match; 
4.  
5.    public HttpConstraint(Func<HttpContextBase, bool> match) 
6.    { 
7.        _match = match; 
8.    } 
9.  
10.    public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection) 
11.    { 
12.        return _match(httpContext); 
13.    } 
14. } 

public class HttpConstraint : IRouteConstraint
{
    private Func<HttpContextBase, bool> _match;

    public HttpConstraint(Func<HttpContextBase, bool> match)
    {
        _match = match;
    }

    public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
    {
        return _match(httpContext);
    }
}