c# - 实现 IActionFilter

Question

我正在构建以下过滤器:

public class TestflowFilter : FilterAttribute, IActionFilter
{
    public void OnActionExecuted(ActionExecutedContext filterContext)
    {
        var profileId = int.Parse(ClaimsPrincipal.Current.GetClaimValue("UserId"));
        var appId = int.Parse(filterContext.RouteData.Values["id"].ToString());

        if (profileId != 0 && appId != 0)
        {
            if (CheckIfValid(profileId, appId))
            {
                 // redirect
                 filterContext.Result = // url to go to
            }
        }
    }

    public void OnActionExecuting(ActionExecutingContext filterContext)
    {
    }

}

我实际上只需要 OnActionExecuted，但由于 IActionFilter 是一个接口(interface)，我必须同时实现它们。如果我不需要任何事情发生，是否可以将 OnActionExecuting 留空，或者我是否需要调用 MVC 始终运行的基本版本？

同样在 OnActionExecuted 方法中，如果 CheckIfValid 为 true，我会重定向用户，但如果不是，我什么都不做。这样可以吗，还是我需要在 filterContext 上设置一些属性。

Answer 1

I actually only need OnActionExecuted, but since IActionFilter is an interface I have to implement them both. Is it ok to leave OnActionExecuting blank if I don't need anything to happen, or do I need to call a base version that MVC always runs?

在这种情况下，将方法主体留空是完全可以接受的。看起来不错!

Also In the OnActionExecuted method if the CheckIfValid is true I redirect the user, but if not I don't do anything, is that ok or do I need to set some property on the filterContext instead.

您的过滤器没问题。 MVC 确实提供了一个名为 ActionFilterAttribute 的不同抽象基类，它实现了这些接口(interface)，供您根据需要覆盖。你有一个很好的概述can read about here .如果您从该类派生，您的过滤器属性代码可以简化一点:

public class TestflowFilter : ActionFilterAttribute
{
    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        var profileId = int.Parse(ClaimsPrincipal.Current.GetClaimValue("UserId"));
        var appId = int.Parse(filterContext.RouteData.Values["id"].ToString());

        if (profileId != 0 && appId != 0)
        {
            if (CheckIfValid(profileId, appId))
            {
                // redirect
                filterContext.Result = // url to go to
            }
        }
    }
}