catch(Exception ex)
{
    Elmah.ErrorSignal.FromCurrentContext().Raise(ex);
}

我试图写自定义消息到elmah日志使用Signal.FromCurrentContext().Raise(ex);并发现这些例外都是冒泡的，例如:

try
{
    ...
}
catch (Exception ex)
{
    Elmah.ErrorSignal.FromCurrentContext().Raise(ex);
    // this will write to the log AND throw the exception
}

此外，我不知道elmah是如何支持不同级别的日志记录的——是否有可能通过web关闭详细日志记录。配置设置?

可以使用Elmah.ErrorSignal()方法记录问题而不引发异常。

try
{
    // Some code
}
catch(Exception ex)
{
    // Log error
    Elmah.ErrorSignal.FromCurrentContext().Raise(ex);

    // Continue
}

使用这条线，它工作得非常好。

 try{
            //Code which may throw an error
    }
    catch(Exception ex){
            ErrorLog.GetDefault(HttpContext.Current).Log(new Elmah.Error(ex));
    }

直接日志写入方法，自ELMAH 1.0开始工作:

try 
{
    some code 
}
catch(Exception ex)
{
    Elmah.ErrorLog.GetDefault(HttpContext.Current).Log(new Elmah.Error(ex));
}

ELMAH 1.2引入了更灵活的API:

try 
{
    some code 
}
catch(Exception ex)
{
    Elmah.ErrorSignal.FromCurrentContext().Raise(ex);
}

这两种解决方案之间存在差异:

Raise方法对异常应用ELMAH过滤规则。日志方法没有。 Raise是基于订阅的，能够将一个异常记录到多个记录器中。

我建议在您自己的一个简单的包装类中包装对Elmah的调用。

using Elmah;

public static class ErrorLog
{
    /// <summary>
    /// Log error to Elmah
    /// </summary>
    public static void LogError(Exception ex, string contextualMessage=null)
    {
        try
        {
            // log error to Elmah
            if (contextualMessage != null) 
            {
                // log exception with contextual information that's visible when 
                // clicking on the error in the Elmah log
                var annotatedException = new Exception(contextualMessage, ex); 
                ErrorSignal.FromCurrentContext().Raise(annotatedException, HttpContext.Current);
            }
            else 
            {
                ErrorSignal.FromCurrentContext().Raise(ex, HttpContext.Current);
            }

            // send errors to ErrorWS (my own legacy service)
            // using (ErrorWSSoapClient client = new ErrorWSSoapClient())
            // {
            //    client.LogErrors(...);
            // }
        }
        catch (Exception)
        {
            // uh oh! just keep going
        }
    }
}

然后在需要记录错误时调用它。

try {
   ...
} 
catch (Exception ex) 
{
    // log this and continue
    ErrorLog.LogError(ex, "Error sending email for order " + orderID);
}

这有以下好处:

You don't need to remember this slightly archaic syntax of the Elmah call If you have many DLLs you don't need to reference Elmah Core from every single one - and just put this in your own 'System' DLL. If you ever need to do any special handling or just want to put in a breakpoint to debug errors you have it all one place. If you ever move away from Elmah you can just change one place. If you have legacy error logging you want to retain (I just happen to have a simple error logging mechanism that's tied into some UIs that I dont immediately have time to remove).

注意:我为上下文信息添加了一个'contextualMessage'属性。如果你愿意，你可以省略这个，但我发现它非常有用。Elmah自动展开异常，因此底层异常仍将在日志中报告，但当您单击contextualMessage时将可见。