script/migrator for easier navigation of migrations

migrator

#!/usr/bin/env ruby

# Simple migration navigator for terminal.
#
# Install
# 1) Throw this code into script/migrator
# 2) chmod +x script/migrator
#
# Alternative install
# 1) Put this script into your executable path (e.g. ~/bin)
# 2) chmod +x ~/bin/migrator
# 3) go to your rails root and use just `migrator` command
#
# Use
# script/migrator       => show 10 latest migrations, choose one
# script/migrator 15    => show 15 latest migrations
# script/migrator -5    => show 5 oldest migrations
# script/migrator foo   => grep all migrations using regexp /foo/
#
# After each command you can:
# — type the # of migration to migrate to it
# — type exit/quit/abort/stop (or press ctrl+c) to exit

require 'time'

search_dirs = [
    File.expand_path(File.join(File.dirname(__FILE__), '..', 'db', 'migrate')),
    File.expand_path(File.join(Dir.pwd, 'db', 'migrate'))
]
migrations_dir = search_dirs.find{|dir| File.exists?(dir)}
globbed_migrations = File.join(migrations_dir, "*.rb")

migrations = []

Dir.glob(globbed_migrations).each do |entry|
  stamp, title = File.basename(entry).split('_', 2)
  title.chomp!('.rb')
  title.gsub!(/_/, ' ')
  title.capitalize!
  migrations << [stamp, title]
end

command = ARGV.join(' ')

run_migration = lambda do |stamp|
  system("rake db:migrate VERSION=#{stamp}")
end

print_results = lambda do |results|
  unless results.empty?
    puts "\n"
    results.each_with_index do |result, i|
      created = Time.parse(result[0]).strftime("%b %d, %y")
      puts "#{i + 1}. #{result[1]}. (#{created})"
    end
    puts "\n"
  end
end

validate_choice = lambda do |results, choice|
  unless (1..results.size).include?(choice.to_i)
    puts "Exiting."
    exit(0)
  end
end

find = lambda do
  results = migrations.select{|el| el[1] =~ Regexp.new(command, "i")}

  puts "Found #{results.size} migration(s):"
  print_results.call(results)

  unless results.empty?
    print "Enter # to migrate to: "
    choice = STDIN.gets.to_i
    validate_choice.call(results, choice)
    puts "Migrating to \"#{results[choice-1][1]}\""
    run_migration.call(results[choice-1][0])
  end
end

first = lambda do |number|
  results = migrations.first(number)

  puts "Showing oldest #{number} migrations:"
  print_results.call(results)

  unless results.empty?
    print "Enter # to migrate to: "
    choice = STDIN.gets.to_i
    validate_choice.call(results, choice)
    puts "Migrating to \"#{results[choice-1][1]}\""
    run_migration.call(results[choice-1][0])
  end
end

last = lambda do |number|
  results = migrations.last(number)

  puts "Showing latest #{number} migrations:"
  print_results.call(results)

  unless results.empty?
    print "Enter # to migrate to: "
    choice = STDIN.gets.to_i
    validate_choice.call(results, choice)
    puts "Migrating to \"#{results[choice-1][1]}\""
    run_migration.call(results[choice-1][0])
  end
end

case command
when /^\s*$/: last.call(10)
when /^(\d+)$/: last.call($1.to_i)
when /^-(\d+)$/: first.call($1.to_i)
else find.call
end