When exactly do OnResultExecuted and OnResultExecu

问题:

I'm creating a custom ActionFilterAttribute in order to transform ViewResults and redirects into JsonResults during ajax requests. I've wired most of it through unit testing and I was for some reason assuming my transformation had to take place in OnResultExecuting, I realized this was not the case, and the correct method to override was OnActionExecuted, which is called as soon as the action method returns a result.

My question is when exactly are OnResultExecuted and OnResultExecuting being called since I've breakpoints in all four overrides and only the ones in OnActionExecuting and OnActionExecuted are firing at all.

回答1:

Let's take the following example which performs the transformation you described:

public class MyActionFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        if (filterContext.HttpContext.Request.IsAjaxRequest())
        {
            var result = filterContext.Result as ViewResultBase;
            if (result != null && result.Model != null)
            {
                filterContext.Result = new JsonResult
                {
                    Data = result.Model,
                    JsonRequestBehavior = JsonRequestBehavior.AllowGet
                };
            }
        }
    }

    public override void OnResultExecuting(ResultExecutingContext filterContext)
    {
    }

    public override void OnResultExecuted(ResultExecutedContext filterContext)
    {
    }
}

The OnResultExecuting method will be invoked immediately before the action result's ExecuteResult method runs and the OnResultExecuted method immediately after.

回答2:

After looking for a while and trying to understand the accepted answer I found this. I believe this shows the order of Execution to be

1. OnActionExecuting
2. OnActionExecuted
3. OnResultExecuting
4. OnResultExecuted

Check this link under listing 2. http://www.asp.net/mvc/overview/older-versions-1/controllers-and-routing/understanding-action-filters-cs