MVC使用Action Filter检查URL中的参数.停止执行

Question

我想做以下事情:

当url没有instID时,我想重定向到该"Instelling"动作

在这个控制器中,每个方法都需要instID.

        [RequiredParameter(parameterName="instID", controllerToSend="Instelling")]
        public ActionResult Index(int? instID) {
            //if (!instID.HasValue) {
            //    return RedirectToAction("Index", "Instelling");
            //}

            var facts = _db.Instellingens.First(q => q.Inst_ID == instID).FacturatieGegevens;

            return View(facts);
        }

所以这是在控制器中.

actionfilter:

namespace MVC2_NASTEST.Controllers {
    public class RequiredParameterAttribute : ActionFilterAttribute {

        public string parameterName { get; set; }
        public string actionToSend { get; set; }
        public string controllerToSend { get; set; }

        public override void OnActionExecuting(ActionExecutingContext filterContext) {

            if (parameterName != string.Empty) {
                if (filterContext.ActionParameters.ContainsKey(parameterName) && filterContext.ActionParameters[parameterName] != null) {
                    string s = "test";
                    //all is good
                } else {
                    //de parameter ontbreekt. kijk of de controller en de action geset zijn.
                    if (actionToSend == string.Empty)
                        actionToSend = "Index";
                    if (controllerToSend == string.Empty) {
                        controllerToSend = filterContext.Controller.ToString();
                        controllerToSend = controllerToSend.Substring(controllerToSend.LastIndexOf(".") + 1);
                        controllerToSend = controllerToSend.Substring(0, controllerToSend.LastIndexOf("Controller"));
                    }

                    UrlHelper helper = new UrlHelper(filterContext.RequestContext);
                    string url = helper.Action(actionToSend, controllerToSend);

                    HttpContext.Current.Response.Redirect(url);
                    //filterContext.HttpContext.Response.Redirect(url, true);
                }
            }

            base.OnActionExecuting(filterContext);
        }

        public override void OnActionExecuted(ActionExecutedContext filterContext) {


            base.OnActionExecuted(filterContext);
        }

    }
}

事情是:它确实有效,然而,动作本身首先被执行,然后重定向发生.这不是我想要的.

也许我不应该使用actionfilters但只是添加路线？在这种情况下,如果缺少instID,我将如何将路由重定向到另一个控制器？

Answer 1

您可以考虑更改为允许您重定向到备用控制器和操作的授权过滤器,而不是创建操作过滤器(在操作方法返回之前运行)

像这样的东西(伪代码):

public class RequiredParameterAttribute : AuthorizeAttribute
{
    protected override bool AuthorizeCore(HttpContextBase httpContext)
    {
        // read instID from QueryString
        // if instId is null, return false, otherwise true
    }

    protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)
    {
        filterContext.result = new RedirectToRouteResult( new { controller = "MyController" , action = "MyAction" }  )
    }

}