ELMAH - Exception Logging without having HttpContext

问题

I tried this solution with Elmah.XmlFileErrorLog but I'm getting following exception

System.ArgumentNullException was unhandled by user code
  Message="Value cannot be null.\r\nParameter name: context"
  Source="Elmah"
  ParamName="context"
  StackTrace:
       at Elmah.ErrorSignal.FromContext(HttpContext context) in c:\builds\ELMAH\src\Elmah\ErrorSignal.cs:line 67
       at Elmah.ErrorSignal.FromCurrentContext() in c:\builds\ELMAH\src\Elmah\ErrorSignal.cs:line 61
       at ElmahHttpErrorHandler.ProvideFault(Exception error, MessageVersion version, Message& fault) in c:\Myapplication\App_Code\Util\ElmahHttpErrorHandler.cs:line 19
       at System.ServiceModel.Dispatcher.ErrorBehavior.ProvideFault(Exception e, FaultConverter faultConverter, ErrorHandlerFaultInfo& faultInfo)
       at System.ServiceModel.Dispatcher.ErrorBehavior.ProvideMessageFaultCore(MessageRpc& rpc)
       at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessageCleanup(MessageRpc& rpc)
  InnerException:

Web.Config file

<configSections>
    <section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings, Microsoft.Practices.EnterpriseLibrary.Logging, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
    <section name="exceptionHandling" type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Configuration.ExceptionHandlingSettings, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
    <section name="dataConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings, Microsoft.Practices.EnterpriseLibrary.Data, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
    <sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
        <sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
            <section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
            <sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
                <section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="Everywhere"/>
                <section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
                <section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
                <section name="roleService" type="System.Web.Configuration.ScriptingRoleServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
            </sectionGroup>
        </sectionGroup>
    </sectionGroup>
  <sectionGroup name="elmah">
    <section name="security" requirePermission="false" type="Elmah.SecuritySectionHandler, Elmah" />
    <section name="errorLog" requirePermission="false" type="Elmah.ErrorLogSectionHandler, Elmah" />
    <section name="errorMail" requirePermission="false" type="Elmah.ErrorMailSectionHandler, Elmah" />
    <section name="errorFilter" requirePermission="false" type="Elmah.ErrorFilterSectionHandler, Elmah" />
  </sectionGroup>
</configSections>
<httpHandlers>
  <add verb="POST,GET,HEAD" path="elmah.axd" type="Elmah.ErrorLogPageFactory, Elmah" />
  <remove verb="*" path="*.asmx"/>
    <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
    <add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
    <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false"/>
</httpHandlers>
<httpModules>
    <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
  <add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" />
</httpModules>
...

<elmah>
  <errorLog type="Elmah.XmlFileErrorLog, Elmah" logPath="~/App_Data" />
  <security allowRemoteAccess="1" />
</elmah>

I'm using windows 7. can there be any problem related to it?

UPDATE Note: I'm running WCF service unders ASP.NET. i.e. I've added WCF Service project to solution by Add New Website and then selecting WCF Service template. I'm currently running it from within IDE. Hosting it on IIS also didn't helped though.

回答1:

I'm answering my own question.

I tried adding following in my web.config

<system.serviceModel>
  <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
</system.serviceModel>

Also decorated my Service with following attribute

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]    
public class CalculatorService : ICalculatorSession    
{
    // Implement calculator service methods
 }

Still no use. Then I got the solution here by which you can use Elmah without HTTPContext. i.e. log errors by writing

Elmah.ErrorLog.GetDefault(null).Log(new Error(ex));

instead of

Elmah.ErrorSignal.FromCurrentContext().Raise(error);

回答2:

Thanks everyone, here is my ErrorHelper class I came up with to manually log errors on websites and in WCF services, windows services, etc:

    public static class ErrorHelper
{
    /// <summary>
    /// Manually log an exception to Elmah.  This is very useful for the agents that try/catch all the errors.
    /// 
    /// In order for this to work elmah must be setup in the web.config/app.config file
    /// </summary>
    /// <param name="ex"></param>
    public static void LogErrorManually(Exception ex)
    {
        if (HttpContext.Current != null)//website is logging the error
        {                
            var elmahCon = Elmah.ErrorSignal.FromCurrentContext();
            elmahCon.Raise(ex);
        }
        else//non website, probably an agent
        {                
            var elmahCon = Elmah.ErrorLog.GetDefault(null);
            elmahCon.Log(new Elmah.Error(ex));
        }
    }
}

回答3:

The only stable solution I could find is to remove the web.config attribute and use the service behavior attribute they use in Exception Logging for WCF Services using ELMAH

回答4:

Are you running this code within ASP.NET? Seems like the HttpContext is null and this is causing the ELmah code to throw the exception -the method Elmah.ErrorSignal.FromCurrentContext() would pass HttpContext.Current from what I remember (been awhile since looked into it) to the Elmah.ErrorSignal.FromContext(HttpContext context) method and this seems to be null, which would not normally be the case in Asp.Net hosted stuff.

Another possibility is that this is occuring outside a request to the server so the HttpContext might be null

来源：https://stackoverflow.com/questions/2997076/elmah-exception-logging-without-having-httpcontext

标签

wcf

elmah

exception-logging