asp.net-mvc – ASP.Net MVC 3：反向授权属性

Conditional Filters in ASP.NET MVC 3

他的解决方案包括编写一个自定义的“条件过滤器提供程序”,允许人们为动作方法的属性指定过滤条件.

细节和推理在他的帖子中,但代码相对简单.首先,创建过滤器提供程序：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;

public class ConditionalFilterProvider : IFilterProvider {
  private readonly 
    IEnumerable<Func<ControllerContext,ActionDescriptor,object>> _conditions;

  public ConditionalFilterProvider(
    IEnumerable<Func<ControllerContext,object>> conditions)
  {

      _conditions = conditions;
  }

  public IEnumerable<Filter> GetFilters(
      ControllerContext controllerContext,ActionDescriptor actionDescriptor) {
    return from condition in _conditions
           select condition(controllerContext,actionDescriptor) into filter
           where filter != null
           select new Filter(filter,FilterScope.Global,null);
  }
}

然后应用它：

IEnumerable<Func<ControllerContext,object>> conditions = 
    new Func<ControllerContext,object>[] { 

    (c,a) => c.Controller.GetType() != typeof(HomeController) ? 
      new MyFilter() : null,(c,a) => a.ActionName.StartsWith("About") ? new SomeFilter() : null
};

var provider = new ConditionalFilterProvider(conditions);
FilterProviders.Providers.Add(provider);