Better error page for Rails and other Rack apps
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README.md

Better Errors

Better Errors replaces the standard Rails error page with a much better and more useful error page. It is also usable outside of Rails in any Rack app as Rack middleware.

image

Features

  • Full stack trace
  • Source code inspection for all stack frames (with highlighting)
  • Local and instance variable inspection
  • Live REPL on every stack frame

Installation

Add this line to your application's Gemfile (under the development group):

group :development do
  gem "better_errors"
end

If you would like to use Better Errors' advanced features (REPL, local/instance variable inspection, pretty stack frame names), you need to add the binding_of_caller gem to your Gemfile:

gem "binding_of_caller"

This is an optional dependency however, and Better Errors will work without it.

Usage

If you're using Rails, there's nothing else you need to do.

If you're not using Rails, you need to insert BetterErrors::Middleware into your middleware stack, and optionally set BetterErrors.application_root if you'd like Better Errors to abbreviate filenames within your application.

Here's an example using Sinatra:

require "sinatra"
require "better_errors"

use BetterErrors::Middleware
BetterErrors.application_root = File.expand_path("..", __FILE__)

get "/" do
  raise "oops"
end

Compatibility

  • Supported
    • MRI 1.9.2, 1.9.3
    • JRuby (1.9 mode) - advanced features unsupported
    • Rubinius (1.9 mode) - advanced features unsupported
  • Coming soon
    • MRI 2.0.0 - the official API for grabbing caller bindings is slated for MRI 2.0.0, but it has not been implemented yet

Known issues

  • Calling yield from the REPL segfaults MRI 1.9.x.

Contributing

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