README.md

How we upgraded UserVoice, a Rails 2.3.14 app, to Ruby 1.9.3.

Blog post here: http://developer.uservoice.com/entries/how-to-upgrade-a-rails-2.3.14-app-to-ruby-1.9.3/

environment.rb

# At the top of environment.rb, set your default encodings:
Encoding.default_external = Encoding.default_internal = Encoding::UTF_8

rails2314_ruby193_monkey_patches.rb

# This little guy is needed unless you want to define a helper for every single one of your controllers
MissingSourceFile::REGEXPS << [/^cannot load such file -- (.+)$/i, 1]

# TZInfo needs to be patched.  In particular, you'll need to re-implement the datetime_new! method:
require 'tzinfo'

module TZInfo
  
  # Methods to support different versions of Ruby.
  module RubyCoreSupport #:nodoc:
    # Ruby 1.8.6 introduced new! and deprecated new0.
    # Ruby 1.9.0 removed new0.
    # Ruby trunk revision 31668 removed the new! method.
    # Still support new0 for better performance on older versions of Ruby (new0 indicates
    # that the rational has already been reduced to its lowest terms).
    # Fallback to jd with conversion from ajd if new! and new0 are unavailable.
    if DateTime.respond_to? :new!
      def self.datetime_new!(ajd = 0, of = 0, sg = Date::ITALY)
        DateTime.new!(ajd, of, sg)
      end
    elsif DateTime.respond_to? :new0
      def self.datetime_new!(ajd = 0, of = 0, sg = Date::ITALY)
        DateTime.new0(ajd, of, sg)
      end
    else
      HALF_DAYS_IN_DAY = rational_new!(1, 2)

      def self.datetime_new!(ajd = 0, of = 0, sg = Date::ITALY)
        # Convert from an Astronomical Julian Day number to a civil Julian Day number.
        jd = ajd + of + HALF_DAYS_IN_DAY
        
        # Ruby trunk revision 31862 changed the behaviour of DateTime.jd so that it will no
        # longer accept a fractional civil Julian Day number if further arguments are specified.
        # Calculate the hours, minutes and seconds to pass to jd.
        
        jd_i = jd.to_i
        jd_i -= 1 if jd < 0
        hours = (jd - jd_i) * 24
        hours_i = hours.to_i
        minutes = (hours - hours_i) * 60
        minutes_i = minutes.to_i
        seconds = (minutes - minutes_i) * 60
        
        DateTime.jd(jd_i, hours_i, minutes_i, seconds, of, sg)
      end
    end
  end
end

# Finally, we have this innocuous looking patch.  Without it, queries like this: current_account.tickets.recent.count
# would instantiate AR objects all (!!) tickets in the account, not merely return a count of the recent ones.
# See https://rails.lighthouseapp.com/projects/8994/tickets/5410-multiple-database-queries-when-chaining-named-scopes-with-rails-238-and-ruby-192
# (The patch in that lighthouse bug was not, in fact, merged in).
module ActiveRecord
  module Associations
    class AssociationProxy   
      def respond_to_missing?(meth, incl_priv)
        false
      end
    end
  end
end

utf8_monkey_patches.rb

# Make sure the logger supports encodings properly.
module ActiveSupport
  class BufferedLogger
    def add(severity, message = nil, progname = nil, &block)
      return if @level > severity
      message = (message || (block && block.call) || progname).to_s

      # If a newline is necessary then create a new message ending with a newline.
      # Ensures that the original message is not mutated.
      message = "#{message}\n" unless message[-1] == ?\n
      buffer << message.force_encoding(Encoding.default_external)
      auto_flush
      message
    end
  end
end

# This makes it so all parameters get converted to UTF-8 before they hit your app.  If someone sends invalid UTF-8 to your server, raise an exception.
# At UserVoice, we rescue this exception and show a custom error page.
class ActionController::InvalidByteSequenceErrorFromParams < Encoding::InvalidByteSequenceError; end
class ActionController::Base

  def force_utf8_params
    traverse = lambda do |val|
      case val
      when Hash
        val.inject(HashWithIndifferentAccess.new) do |hash, (key, val)|
          hash[key] = traverse.call val
          hash
        end
      when Array
        val.map { |val| traverse.call val }
      else
        val.respond_to?(:force_encoding) ? val.dup.force_encoding(Encoding.default_external) : val
      end
    end
    # We want to build a new hash and inject those values into zie existing hash, koz?
    self.params = traverse.call params

    path_str = request.path.to_s
    if path_str.respond_to?(:force_encoding)
      path_str.force_encoding(Encoding.default_external)
      raise ActionController::InvalidByteSequenceErrorFromParams unless path_str.valid_encoding?
    end
  end
  before_filter :force_utf8_params
end

# Serialized columns in AR don't support UTF-8 well, so set the encoding on those as well.
class ActiveRecord::Base
  def unserialize_attribute_with_utf8(attr_name)
    traverse = lambda do |object, block|
      if object.kind_of?(Hash)
        object.each_value { |o| traverse.call(o, block) }
      elsif object.kind_of?(Array)
        object.each { |o| traverse.call(o, block) }
      else
        block.call(object)
      end
      object
    end
    force_encoding = lambda do |o|
      o.force_encoding(Encoding::UTF_8) if o.respond_to?(:force_encoding)
    end
    value = unserialize_attribute_without_utf8(attr_name)
    traverse.call(value, force_encoding)
  end
  alias_method_chain :unserialize_attribute, :utf8
end

# Make sure the flash sets the encoding to UTF-8 as well.
module ActionController
  module Flash
    class FlashHash
      def [](k)
        v = super
        v.is_a?(String) ? v.force_encoding("UTF-8") : v
      end
    end
  end
end