Auto-Patch Rails — err.the

Want to use a patch from the Rails’ Trac that DHH didn’t think was a good fit? Patching some core functionality of Rails that you don’t want to make into a plugin?

Place the following code in config/environment.rb before boot.rb is required.

require File.join(File.dirname(__FILE__), '../lib/rails_patcher')
Rails::Patcher.run

And this into lib/rails_patcher.rb

module Rails
  module Patcher
    ROOT_DIR = File.join(File.dirname(__FILE__), '..')
    PATCHES_DIR = "#{ROOT_DIR}/lib/patches/"

    def self.run
      `mkdir #{PATCHES_DIR}` unless File.directory?(PATCHES_DIR)
      `rake rails:freeze:gems` unless File.directory?("#{ROOT_DIR}/vendor/rails")

      Dir["#{PATCHES_DIR}/*"].each do |file|
        next if %w(. ..).include?(file) || file =~ /^APPLIED_/
        STDERR.print "Patching #{file}..."
        `patch -d #{ROOT_DIR}/vendor/rails -p0 < #{PATCHES_DIR}/#{file}`
        STDERR.print "Done.\n"
        `mv #{PATCHES_DIR}/#{file} #{PATCHES_DIR}/APPLIED_#{file}`
      end
    end
  end
end

All that is left is for you is to drop your diff’s into lib/patches, start your server, and the patches are automatically applied once to vendor/rails

The only caveat is that this won’t work if you’re on Windows. Other than that, the code is fairly straightforward if you have any questions about what’s going on.

Update: using the right rake task to freeze the rails gems now.