37

I am working on rails project and I am trying to get exceptions to be logged to the rails log files. I know I can call logger.error $! to get the first line of the exception logged to the file. But, I want to get the entire trace stack logged as well. How do I log the entire trace back of an exception using the default rails logger?

Andy Lester
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Josh Moore
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7 Answers7

38
logger.error $!.backtrace

Also, don't forget you can 

rescue ErrorType => error_name

to give your error a variable name other than the default $!.

Ian Terrell
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    Am I missing something? logger.error only takes a single argument, so that code does not work... – Robin Clowers Feb 29 '12 at 22:39
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    This one doesn't work, use `logger.error e.message + "\n " + e.backtrace.join("\n ")` instead. – Jonas Fagundes May 05 '12 at 06:31
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    I could swear the multiple parameters worked 4 years ago, but maybe it didn't. I've updated it to just log the backtrace, which seems to be the most relevant aspect of the question; I trust the reader can figure out multiple logger calls are possible, ditto for string concatenation (or more Ruby-y, interpolation). – Ian Terrell May 05 '12 at 14:44
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    don't do join('\n') single quotes :p – James Jul 25 '14 at 15:55
18

The way rails does it is

137             logger.fatal(
138               "\n\n#{exception.class} (#{exception.message}):\n    " +
139               clean_backtrace(exception).join("\n    ") +
140               "\n\n"
141             )

248       def clean_backtrace(exception)
249         if backtrace = exception.backtrace
250           if defined?(RAILS_ROOT)
251             backtrace.map { |line| line.sub RAILS_ROOT, '' }
252           else
253             backtrace
254           end
255         end
256       end
Matt Burke
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10

In later versions of Rails, simply uncomment the following line in RAIL_ROOT/config/initializers/backtrace_silencers.rb (or add this file itself if it's not there):

# Rails.backtrace_cleaner.remove_silencers!

This way you get the full backtrace written to the log on an exception. This works for me in v2.3.4.

mxgrn
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    It's part of the documentation for Rails 3.2.3. See here: http://api.rubyonrails.org/classes/ActiveSupport/BacktraceCleaner.html – Rob May 25 '12 at 15:13
6

logger.error caller.join("\n") should do the trick.

Redbeard
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4

In Rails, ActionController::Rescue deals with it. In my application controller actions, i'm using method log_error from this module to pretty-format backtrace in logs:

def foo_action
  # break something in here
rescue
  log_error($!)
  # call firemen
end
Priit
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3

Here's how I would do it:

http://gist.github.com/127708

Here's the ri documentation for Exception#backtrace:

http://gist.github.com/127710

Note that you could also use Kernel#caller, which gives you the full trace (minus the curent frame) as well.

http://gist.github.com/127709

Also - Note that if you are trying to catch all exceptions, you should rescue from Exception, not RuntimeError.

user52804
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1

You can also use ruby's default variables, like this:

logger.error "Your error message. Exception message:#{$!} Stacktrace:#{$@}"
user3223833
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