How to catch all exceptions in ruby?

Question

How can we catch or/and handle all unhandled exceptions in ruby?

The motivation for this is maybe logging some kind of exceptions to different files or send and e-mail to the system administration, for example.

In Java we will do

Thread.setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler ex);

In NodeJS

process.on('uncaughtException', function(error) {
   /*code*/
});

In PHP

register_shutdown_function('errorHandler');

function errorHandler() { 
    $error = error_get_last();
    /*code*/    
}

How can we do this with ruby?

score 11 · Answer 1 · edited May 23 '17 at 11:53

11

Advanced solution use exception_handler gem

If you want just to catch all exceptions and put for example in your logs, you can add following code to ApplicationController:

begin
  # do something dodgy
rescue ActiveRecord::RecordNotFound
  # handle not found error
rescue ActiveRecord::ActiveRecordError
  # handle other ActiveRecord errors
rescue # StandardError
  # handle most other errors
rescue Exception
  # handle everything else
end

More details you can find in this thread.

edited May 23 '17 at 11:53

Community

1
1

answered Feb 03 '17 at 17:53

w1t3k

228
2
12

`rescue Exception` is really [heavy handed](http://stackoverflow.com/questions/10048173/why-is-it-bad-style-to-rescue-exception-e-in-ruby). You could mention why it's generally a bad idea. – Eric Duminil Feb 03 '17 at 20:42
Thanks for you comment, I wasn't aware of that yet. – w1t3k Feb 05 '17 at 11:19
No problem. `rescue Exception` is like putting a snooze button on a fire alarm. You can do it, but you probably shouldn't ;) – Eric Duminil Feb 05 '17 at 15:18
1

Isn't ApplicationController part of Rails? – Rob Raisch Jan 25 '19 at 19:26

score 3 · Answer 2 · answered Feb 03 '17 at 17:24

3

In Ruby you would just wrap your program around a begin / rescue / end block. Any unhandled exception will bubble up to that block and be handled there.

answered Feb 03 '17 at 17:24

Carl Tashian

159
4

Is this works even if we have an exception being thrown from another file or by a third party library? – GarouDan Feb 03 '17 at 17:31

How to catch all exceptions in ruby?

2 Answers2