CODEWITHSUNDEEP
c#asp.netexception
Roland
Roland

Reputation: 5234

catch exceptions from all Pages

I am trying to log all "general errors" from the site I am maintaining, to debug the code-behind, without having to show the detailed error page to the users. The web.config says:

<customErrors mode="RemoteOnly" defaultRedirect="~/GeneralError.html"/>

which works for problems like divide by zero, null-reference exceptions, missing dll, etc. After lots of reading here I found that these are the "unhandled exceptions", but do not reach the handler Application_Error() in global.asax. What does work, on a per-page basis, is:

protected override void OnError(EventArgs e)
{
    Exception TheException = Server.GetLastError();
    // todo: log the exception to the database
    base.OnError(e); //pass the exception to the regular handler
    return;
}

But could this be changed to log the unhandled exceptions of all pages with a single method? How can I overwrite, or modify, the base class Page?

I also thought of put logging in the code-behind of GeneralError.aspx, but then there would be no stack trace or exception message, and also any user may call this page directly just to annoy us.

I investigated using some IErrorHandler interface mentioned in some posts, but this should relate to WinForm apps, not to asp.net web apps.

Upvotes: 0

Views: 733

Answers (3)

Roland
Roland

Reputation: 5234

I am currently studying https://msdn.microsoft.com/en-us/library/aa479332.aspx, found through https://stackoverflow.com/a/138088/1845672 which talks about exactly my problem with the exact same approach: provide a solution to log errors on all pages in a maintainable way without modifying all pages.

The download link on the microsoft site is stale. According to: https://code.google.com/p/elmah/issues/detail?id=64 the sources are moved from the microsoft site to: elmah.googlecode.com/files/GDN-ELMAH-1.0.5527-setup.zip .

Looks like this is a complete solution . . .

Upvotes: 0

Mat Forsberg
Mat Forsberg

Reputation: 454

Create a new class:

public class MyPage : System.Web.UI.Page
{
     protected override void OnError(EventArgs e)
     {
         Exception TheException = Server.GetLastError();
         // todo: log the exception to the database
         base.OnError(e); //pass the exception to the regular handler
         return;
     }
}

and instead of inheriting from System.Web.UI.Page inherit from MyPage on your individual pages.

Upvotes: 0

STORM
STORM

Reputation: 4331

Use the Application_Error method in your Global.asax file.

Inside your Application_Error method implementation call Server.GetLastError(), log the details of the exception returned by Server.GetLastError().

Exception LastError;
String ErrMessage;

LastError = Server.GetLastError();

if (LastError != null)
   ErrMessage = LastError.Message;
else
   ErrMessage = "No Errors";

Response.Write("Last Error = " + ErrMessage);

See here at MSDN or if you want a complete Microsoft Example at Complete Example for Error Handlers.

Upvotes: 2

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