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

最近監控線上日誌，網站是ASP.NET MVC 開發的，發現很多錯誤日誌都記錄一樣的內容：

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)

本地調試下不會發現，經過排查發現本地和線上配置的差別在於 customErrors mode="On"，將本地改後單點調試發現確實是將這樣的錯誤記錄，而自己我在action裏面 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，而記錄的是一個可有可無莫名其妙的日誌，由於我並無任何代碼去返回」Error「這個view。

先說下目前我抓取異常的方式：在Global.asax文件中增長

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

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

煩了好久，最後不經意發現MVC裏面會默認註冊一個Filter，代碼以下

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

註冊掉能夠解決上述問題，可是我不太服氣，因而在codeplex翻了mvc的源代碼，HandleErrorAttribute的代碼以下：

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裏面會默認返回error視圖，看來之後新開發時仍是建立空項目好了。

至於爲啥設置了customErrors mode="On"後纔會出現這種垃圾日誌，則要歸咎於HandleErrorAttribute類的OnException方法裏面了

        // 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;
            }

 

解決方案是刪掉默認註冊的這個filter或者新增類去override相應的方法。