Fix old Rails 1.x finder syntax.

fix_find_all.rb

#!/usr/bin/env ruby

# A script to convert old Rails 1.x finder syntax, e.g. find(:all, ...) and find(:first, ...)
# to use where() and friends.

# gem install parser unparser
# cd path/to/rails_app
# ruby fix_find_by.rb

require 'parser/current'
require 'unparser'
require 'pry'

class RewriteFindBy < Parser::Rewriter
  def on_send(node)
    method_name = node.location.selector.source
    if method_name == 'find'
      args = node.to_a[2..-1].map { |a| Unparser.unparse(a) }
      final = "#{Unparser.unparse(node.to_a[0])}"
      if [":all", ":first"].include?(args.first)
        node.to_a[3..-1].each do |arg|
          arg.children.each do |pair|
            begin
              (key, val) = [Unparser.unparse(pair.children.first), Unparser.unparse(pair.children.last)]
            rescue NoMethodError
              next
            end
            case key.to_s
            when ":conditions"
              final << ".where(#{val.gsub(/^\[|\]$/, '')})"
            when ":order"
              final << ".order(#{val})"
            when ":include"
              final << ".includes(#{val})"
            when ":limit"
              final << ".limit(#{val})"
            when ":offset"
              final << ".offset(#{val})"
            when ":join"
              final << ".join(#{val})"
            when ":select"
              final << ".select(#{val})"
            when ":page"
              final << ".page(#{val})"
            when ":per_page"
              final << ".paginate(per_page: #{val})"
            end
          end
        end
        final << ".first" if args.first == ":first"
        replace(node.location.expression, final)
      end
    end
    node.to_a.each do |n|
      if n.respond_to?(:type) and n.type
        send("on_#{n.type}".to_sym, n) rescue nil
      end
    end
  end

  %w(on_argument on_casgn on_const on_def on_defs on_op_asgn on_var on_vasgn
     process_argument_node process_regular_node process_var_asgn_node process_variable_node).each do |event|
    define_method(event) do |node|
      node.to_a.each do |n|
        if n.respond_to?(:type) and n.type
          ev = "on_#{n.type}".to_sym
          send(ev, n) if respond_to?(ev)
        end
      end
    end
  end
end

Dir['**/*.rb', '**/*.rake'].each do |path|
  puts path
  buffer = Parser::Source::Buffer.new(path)
  buffer.source = File.read(path)
  parser = Parser::CurrentRuby.new
  begin
    ast = parser.parse(buffer)
  rescue Parser::SyntaxError
    puts "could not parse #{path}"
  else
    rewriter = RewriteFindBy.new
    source = rewriter.rewrite(buffer, ast)
    File.open(path, 'w') { |f| f.write(source) }
  end
end