ExceptionFormatter

Note: There is also a gem named exception-formatter (dash not underscore) and maybe you're looking for that.

Purpose

I was sick of writing "#{exception.class.name}: #{exception.message}\n#{exception.backtrace.join("\n")}" and alike.

Simple formatter for ruby exception messages.

Features:

Custom format pattern
Nested exception support (see gems like nested_exceptions, nestegg, nesty)
ActiveRecord:::RecordInvalid exception support

Installation

Add this line to your application's Gemfile:

gem 'exception_formatter'

And then execute:

$ bundle

Or install it yourself as:

$ gem install exception_formatter

Examples

Using default pattern

If no pattern is given the default pattern is used (see ExceptionFormatter::DEFAULT_PATTERN):

begin
  ... code ... code ... code
rescue => ex
  logger.error ExceptionFormatter.format(ex)
end

Will produce the string:

  StandardError: the exception message
  file:31
  file:76

Using custom pattern

begin
  ... code ... code ... code
rescue => ex
  logger.error ExceptionFormatter.format(ex, pattern: "[%k] %m\nStacktrace:\n%b")
end

Will produce the string:

  [StandardError] the exception message
  Stacktrace:
  file:31
  file:76

Alternatively use instance method:

FORMATTER = ExceptionFormatter.new(pattern: "[%k] %m\n%b")

begin
  ... code ... code ... code
rescue => ex
  logger.error FORMATTER.format(ex)
end

Available pattern

%b         = exception backtrace, lines joined with "\n"
%c         = cause, the nested exception message (by calling exception.cause.message)
%c{method} = cause, the nested exception message (by calling exception.method.message)
             (useful if nested exception does not respond to #cause but to #reason or what ever)
%k         = exception class name
%m         = exception message
%r         = record errors, the record error messages in case of ActiveRecord:::RecordInvalid exception
             (by calling exception.record.errors.full_messages)
%x{method} = message return by calling exception.send(method)

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request