问题
I just started using ELMAH and am a fan. My team supports a large number of web applications and I\'m particularly excited that ELMAH lets us save exceptions from each application to the same MS SQL database table.
We also support a few console, DLL and desktop applications. Is it possible to use the ELMAH DLL to log exceptions in these apps to that same location?
回答1:
We have exactly the same situation here. Running ELMAH for all our web applications. A few of them have console based schedulers.
After doing some digging through the source code, the following code seems to work:
ErrorLog errorLog = ErrorLog.GetDefault(null);
errorLog.ApplicationName = "/LM/W3SVC/1/ROOT/AppName";
errorLog.Log(new Error(ex));
The only real problem with the above is that you need to keep the application name somewhere in your config to be able to see the entries on the ELMAH.axd viewer.
So in our generic error handling code we do:
if (HttpContext.Current != null)
ErrorSignal.FromCurrentContext().Raise(ex);
else
{
ErrorLog errorLog = ErrorLog.GetDefault(null);
errorLog.ApplicationName = ErrorHandling.Application;
errorLog.Log(new Error(ex));
}
回答2:
We needed the ability to log from a console app and a windows service in addition to our ASP.NET site. I used the answer (ErrorLog.GetDefault(null);) which worked well until I needed to email too.
So, here is my solution. It handles the log, email, tweet and filtering (both in the config file and in code). I have also wrapped the main call as an extension to Exception so it can be called like: catch(Exception ex) { ex.LogToElmah(); }
To filter in code, hook the corresponding .Filtering event: ElmahExtension.ErrorLog.Filtering += new ExceptionFilterEventHandler(ErrorLog_Filtering);
Code:
using System;
using System.Web;
using Elmah;
namespace System
{
public static class ElmahExtension
{
public static void LogToElmah(this Exception ex)
{
if (HttpContext.Current != null)
{
ErrorSignal.FromCurrentContext().Raise(ex);
}
else
{
if (httpApplication == null) InitNoContext();
ErrorSignal.Get(httpApplication).Raise(ex);
}
}
private static HttpApplication httpApplication = null;
private static ErrorFilterConsole errorFilter = new ErrorFilterConsole();
public static ErrorMailModule ErrorEmail = new ErrorMailModule();
public static ErrorLogModule ErrorLog = new ErrorLogModule();
public static ErrorTweetModule ErrorTweet = new ErrorTweetModule();
private static void InitNoContext()
{
httpApplication = new HttpApplication();
errorFilter.Init(httpApplication);
(ErrorEmail as IHttpModule).Init(httpApplication);
errorFilter.HookFiltering(ErrorEmail);
(ErrorLog as IHttpModule).Init(httpApplication);
errorFilter.HookFiltering(ErrorLog);
(ErrorTweet as IHttpModule).Init(httpApplication);
errorFilter.HookFiltering(ErrorTweet);
}
private class ErrorFilterConsole : ErrorFilterModule
{
public void HookFiltering(IExceptionFiltering module)
{
module.Filtering += new ExceptionFilterEventHandler(base.OnErrorModuleFiltering);
}
}
}
}
In addition, you will need to add a reference to the System.Web.dll in your project for this to work.
EDIT: As per the comments, this code will send emails only if your config file has <errorMail async="false"/>. Refer to this code snippet should you want to keep <errorMail async="true"/> in your config file (to be used when HttpContext.Current is available).
回答3:
If you just want to email the log without http you can do like this:
public class MyElmahMail: ErrorMailModule
{
public MyElmahMail()
{
//this basically just gets config from errorMail (app.config)
base.OnInit(new HttpApplication());
}
public void Log(Error error)
{
//just send the email pls
base.ReportError(error);
}
}
//to call it
var mail = new MyElmahMail();
mail.Log(new Error(new NullReferenceException()));//whatever exception u want to log
And in terms of app.config
//Under configSections
<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>
And
<elmah>
<errorLog type="Elmah.XmlFileErrorLog, Elmah" logPath="C:\Elmah.Error" applicationName="MyAwesomeApp" />
<errorMail from="from@email.com" to="to@email.com" />
</elmah>
And smtp settings of your choice.
All done. :-)
回答4:
Edit: This CAN be done - See this answer.
I'm pretty sure you can't do this. I'll try and dig up the relevant material.
http://groups.google.com/group/elmah/browse_thread/thread/f214c4f782dc2bf4/d96fe43b60765f0c?lnk=gst&q=app#d96fe43b60765f0c
So from what I can find searching the Google group is that it's not possible... Since ELMAH works off of HttpHandlers (an asp.net construct) it is ASP.NET only.
With that said, there are ways that you could utilize it on a console application. ELMAH provides a method to raise errors, so you could wrap ELMAH in your exception handling and then signal an error via:
ErrorSignal.FromCurrentContext().Raise(new NotSupportedException());
This would mean wrapping your entire application in an exception handler and signaling. It might take you some tweaking to get it down, but I think it's totally possible.
In case you require it, this is the link to the ELMAH code repository.
回答5:
For those that need Brian Chance's answer ported to VB.NET:
Imports System
Imports System.Web
Imports Elmah
Namespace System
Public NotInheritable Class ElmahExtension
Private Sub New()
End Sub
<System.Runtime.CompilerServices.Extension> _
Public Shared Sub LogToElmah(ex As Exception)
If HttpContext.Current IsNot Nothing Then
ErrorSignal.FromCurrentContext().Raise(ex)
Else
If httpApplication Is Nothing Then
InitNoContext()
End If
ErrorSignal.[Get](httpApplication).Raise(ex)
End If
End Sub
Private Shared httpApplication As HttpApplication = Nothing
Private Shared errorFilter As New ErrorFilterConsole()
Public Shared ErrorEmail As New ErrorMailModule()
Public Shared ErrorLog As New ErrorLogModule()
Public Shared ErrorTweet As New ErrorTweetModule()
Private Shared Sub InitNoContext()
httpApplication = New HttpApplication()
errorFilter.Init(httpApplication)
TryCast(ErrorEmail, IHttpModule).Init(httpApplication)
errorFilter.HookFiltering(ErrorEmail)
TryCast(ErrorLog, IHttpModule).Init(httpApplication)
errorFilter.HookFiltering(ErrorLog)
TryCast(ErrorTweet, IHttpModule).Init(httpApplication)
errorFilter.HookFiltering(ErrorTweet)
End Sub
Private Class ErrorFilterConsole
Inherits Elmah.ErrorFilterModule
Public Sub HookFiltering([module] As Elmah.IExceptionFiltering)
AddHandler [module].Filtering, New Elmah.ExceptionFilterEventHandler(AddressOf MyBase.OnErrorModuleFiltering)
End Sub
End Class
End Class
End Namespace
However, for just logging errors to the database, this will be sufficient:
If System.Web.HttpContext.Current Is Nothing Then
Dim req As System.Web.HttpRequest = New System.Web.HttpRequest(String.Empty, "https://www.domain.tld", Nothing)
Dim res As System.Web.HttpResponse = New System.Web.HttpResponse(Nothing)
System.Web.HttpContext.Current = New System.Web.HttpContext(req, res)
'Dim request As System.Web.Hosting.SimpleWorkerRequest = New System.Web.Hosting.SimpleWorkerRequest("/blah", "c:\inetpub\wwwroot\blah", "blah.html", Nothing, New System.IO.StringWriter())
'System.Web.HttpContext.Current = New System.Web.HttpContext(request)
System.Web.HttpContext.Current.ApplicationInstance = New System.Web.HttpApplication()
Dim ErrorLog As New Elmah.ErrorLogModule()
TryCast(ErrorLog, System.Web.IHttpModule).Init(System.Web.HttpContext.Current.ApplicationInstance)
End If
As a complete solution:
Public parent As Elmah.ServiceProviderQueryHandler = Nothing
' http://stackoverflow.com/questions/5981750/configuring-elmah-with-sql-server-logging-with-encrypted-connection-string
Public Function Elmah_MS_SQL_Callback(objContext As Object) As System.IServiceProvider
Dim container As New System.ComponentModel.Design.ServiceContainer(parent(objContext))
Dim strConnectionString As String = COR.SQL.MS_SQL.GetConnectionString()
Dim log As Elmah.SqlErrorLog = New Elmah.SqlErrorLog(strConnectionString)
'Dim strApplicationName = System.Web.Compilation.BuildManager.GetGlobalAsaxType().BaseType.Assembly().FullName
Dim strApplicationName As String = System.Reflection.Assembly.GetExecutingAssembly().FullName
If Not String.IsNullOrEmpty(strApplicationName) Then
log.ApplicationName = strApplicationName.Substring(0, strApplicationName.IndexOf(","))
End If
container.AddService(GetType(Elmah.ErrorLog), log)
Return container
End Function ' Elmah_MS_SQL_Callback
Public Function Elmah_PG_SQL_Callback(objContext As Object) As System.IServiceProvider
Dim container As New System.ComponentModel.Design.ServiceContainer(parent(objContext))
Dim strConnectionString As String = COR.SQL.MS_SQL.GetConnectionString()
Dim log As Elmah.PgsqlErrorLog = New Elmah.PgsqlErrorLog(strConnectionString)
'Dim strApplicationName = System.Web.Compilation.BuildManager.GetGlobalAsaxType().BaseType.Assembly().FullName
Dim strApplicationName As String = System.Reflection.Assembly.GetExecutingAssembly().FullName
If Not String.IsNullOrEmpty(strApplicationName) Then
log.ApplicationName = strApplicationName.Substring(0, strApplicationName.IndexOf(","))
End If
container.AddService(GetType(Elmah.ErrorLog), log)
Return container
End Function ' Elmah_PG_SQL_Callback
' http://weblogs.asp.net/stevewellens/archive/2009/02/01/debugging-a-deployed-site.aspx
Public Sub Initialize()
If System.Web.HttpContext.Current Is Nothing Then
Dim req As System.Web.HttpRequest = New System.Web.HttpRequest(String.Empty, "https://www.domain.tld", Nothing)
Dim res As System.Web.HttpResponse = New System.Web.HttpResponse(Nothing)
System.Web.HttpContext.Current = New System.Web.HttpContext(req, res)
'Dim request As System.Web.Hosting.SimpleWorkerRequest = New System.Web.Hosting.SimpleWorkerRequest("/blah", "c:\inetpub\wwwroot\blah", "blah.html", Nothing, New System.IO.StringWriter())
'System.Web.HttpContext.Current = New System.Web.HttpContext(request)
System.Web.HttpContext.Current.ApplicationInstance = New System.Web.HttpApplication()
Dim ErrorLog As New Elmah.ErrorLogModule()
TryCast(ErrorLog, System.Web.IHttpModule).Init(System.Web.HttpContext.Current.ApplicationInstance)
End If
parent = Elmah.ServiceCenter.Current
If SQL.IsMsSql Then
Elmah.ServiceCenter.Current = AddressOf Elmah_MS_SQL_Callback
End If
If SQL.IsPostGreSql Then
Elmah.ServiceCenter.Current = AddressOf Elmah_PG_SQL_Callback
End If
End Sub ' InitializeElmah
And
Elmah.ErrorSignal.FromCurrentContext().Raise(New NotImplementedException("Test"))
will work if it is called after Initialize()
回答6:
Well, since I can't comment I'll post this down here and maybe someone will see it.
After following Brian's method and the commentors I was able to get email working but I still wasn't seeing the SQL messages being logged, even though I had set the applicationName. What I didn't realize is that they were actually being logged I just wasn't seeing them because the applicationName must be the same as your web.config in order to be able to view it.
My web.config didn't have applicationName specified, so it was defaulting to "/LM/W3SVC/2/ROOT", which is basically what "asgeo1" commented, though I didn't realize it had to be the same.
Since I didn't really have any errors I was concerned with, I configured applicationName in my web.config and my app.config to be the same and now everything shows up like a champ.
<errorLog type="Elmah.SqlErrorLog, Elmah" connectionStringName="ELMAH" applicationName="MyAppName" />
回答7:
ELMAH stands for Error Logging Modules and Handlers - referring, of course, to IHttpModule and IHttpHandler.
Console applications do not use HTTP, so would typically not be able to benefit much from Modules and Handlers built for HTTP.
来源：https://stackoverflow.com/questions/841451/using-elmah-in-a-console-application