記處理線上記錄垃圾日誌 The view 'Error' or its master was not found

dong.net發表於2015-07-10
ViewErrorAST

最近監控線上日誌，網站是ASP.NET MVC 開發的，發現不少錯誤日誌都記錄同樣的內容：

The view 'Error' or its master was not found or no view engine supports the searched locations. The following locations were searched:
~/Views/Search/Error.aspx
~/Views/Search/Error.ascx
~/Views/Shared/Error.aspx
~/Views/Shared/Error.ascx
~/Views/Search/Error.cshtml
~/Views/Search/Error.vbhtml
~/Views/Shared/Error.cshtml
~/Views/Shared/Error.vbhtml
System.Web.Mvc
   at System.Web.Mvc.ViewResult.FindView(ControllerContext context)

本地除錯下不會發現，通過排查發現本地和線上配置的差異在於 customErrors mode="On"，將本地改後單點除錯發現確實是將這樣的錯誤記錄，而本身我在action裡面 throw 出來的異常已經抓取不到了。也就是說真的異常並未抓取到，而記錄的是一個無關緊要莫名其妙的日誌，因為我並沒有任何程式碼去返回”Error“這個view。

先說下目前我抓取異常的方式：在Global.asax檔案中增加

        protected void Application_Error(object sender, EventArgs e)
        {
            Exception ex = Server.GetLastError();
            //Write Log
        }

假如在Controller裡面去override OnException方法進行寫日誌則不會出現這樣的問題，但是在Controller裡記日誌可能會使在View裡面出錯的日誌記錄不到。

煩了很久，最後不經意發現MVC裡面會預設註冊一個Filter，程式碼如下

        public static void RegisterGlobalFilters(GlobalFilterCollection filters)
        {
            filters.Add(new HandleErrorAttribute());
        }

註冊掉可以解決上述問題，但是我不太服氣，於是在codeplex翻了mvc的原始碼，HandleErrorAttribute的程式碼如下：

using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Web.Mvc.Properties;

namespace System.Web.Mvc
{
    [SuppressMessage("Microsoft.Performance", "CA1813:AvoidUnsealedAttributes", Justification = "This attribute is AllowMultiple = true and users might want to override behavior.")]
    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = true)]
    public class HandleErrorAttribute : FilterAttribute, IExceptionFilter
    {
        private const string DefaultView = "Error";

        private readonly object _typeId = new object();

        private Type _exceptionType = typeof(Exception);
        private string _master;
        private string _view;

        public Type ExceptionType
        {
            get { return _exceptionType; }
            set
            {
                if (value == null)
                {
                    throw new ArgumentNullException("value");
                }
                if (!typeof(Exception).IsAssignableFrom(value))
                {
                    throw new ArgumentException(String.Format(CultureInfo.CurrentCulture,
                                                              MvcResources.ExceptionViewAttribute_NonExceptionType, value.FullName));
                }

                _exceptionType = value;
            }
        }

        public string Master
        {
            get { return _master ?? String.Empty; }
            set { _master = value; }
        }

        public override object TypeId
        {
            get { return _typeId; }
        }

        public string View
        {
            get { return (!String.IsNullOrEmpty(_view)) ? _view : DefaultView; }
            set { _view = value; }
        }

        public virtual void OnException(ExceptionContext filterContext)
        {
            if (filterContext == null)
            {
                throw new ArgumentNullException("filterContext");
            }
            if (filterContext.IsChildAction)
            {
                return;
            }

            // If custom errors are disabled, we need to let the normal ASP.NET exception handler
            // execute so that the user can see useful debugging information.
            if (filterContext.ExceptionHandled || !filterContext.HttpContext.IsCustomErrorEnabled)
            {
                return;
            }

            Exception exception = filterContext.Exception;

            // If this is not an HTTP 500 (for example, if somebody throws an HTTP 404 from an action method),
            // ignore it.
            if (new HttpException(null, exception).GetHttpCode() != 500)
            {
                return;
            }

            if (!ExceptionType.IsInstanceOfType(exception))
            {
                return;
            }

            string controllerName = (string)filterContext.RouteData.Values["controller"];
            string actionName = (string)filterContext.RouteData.Values["action"];
            HandleErrorInfo model = new HandleErrorInfo(filterContext.Exception, controllerName, actionName);
            filterContext.Result = new ViewResult
            {
                ViewName = View,
                MasterName = Master,
                ViewData = new ViewDataDictionary<HandleErrorInfo>(model),
                TempData = filterContext.Controller.TempData
            };
            filterContext.ExceptionHandled = true;
            filterContext.HttpContext.Response.Clear();
            filterContext.HttpContext.Response.StatusCode = 500;

            // Certain versions of IIS will sometimes use their own error page when
            // they detect a server error. Setting this property indicates that we
            // want it to try to render ASP.NET MVC's error page instead.
            filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
        }
    }
}
HandleErrorAttribute

坑爹，他mvc裡面會預設返回error檢視，看來以後新開發時還是建立空專案好了。

至於為啥設定了customErrors mode="On"後才會出現這種垃圾日誌，則要歸咎於HandleErrorAttribute類的OnException方法裡面了

        // If custom errors are disabled, we need to let the normal ASP.NET exception handler
            // execute so that the user can see useful debugging information.
            if (filterContext.ExceptionHandled || !filterContext.HttpContext.IsCustomErrorEnabled)
            {
                return;
            }

 

解決方案是刪掉預設註冊的這個filter或者新增類去override相應的方法。

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