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We recently needed to create a new database migration, and needed to insert it into at certain position. Normally what I have done in the past is to alter the migration index of an existing file or two.

But this time, it needed to go in at 003. I was going to have to manually increment about 30 or 40 migration scripts. So, it was time to apply my Ruby skills to do it automatically.

Here is the result:

<br /> #!/usr/bin/ruby<br /> #<br /> # Increments the number in Rails migrations from a given starting index. Run<br /> # this in the db/migrations directory only.<br /> #<br /> # Example:<br /> #<br /> # increment_migrations 3 RUN<br /> #<br /> # this would add 1 to to all your migrations from 003_create_XXXXX.rb onwards</p> <p>case ARGV.size<br /> when 1, 2<br /> from_index = ARGV[0].to_i<br /> dir = Dir.new(‘.’)<br /> file_list = dir.to_a.sort</p> <p> file_list.each do |fn|<br /> if fn =~ /(\d{3})(.*\.rb)/<br /> index = $1.to_i<br /> if index >= from_index<br /> index += 1<br /> new_name = case index.to_s.length<br /> when 1<br /> “00#{index}#{$2}”<br /> when 2<br /> “0#{index}#{$2}”<br /> else<br /> “#{index}#{$2}”<br /> end<br /> puts “Converting ‘#{fn}’ to ‘#{new_name}’”<br /> File.rename fn, new_name if ARGV[1] == “RUN”<br /> else<br /> puts “Skipping ‘#{fn}’”<br /> end<br /> else<br /> puts “Ignoring ‘#{fn}’”<br /> end<br /> end<br /> else<br /> puts “Usage: #{$0} <number> [RUN]“<br /> puts ” where”<br /> puts ” number – migration number to start from (mandatory)”<br /> puts ” RUN – add to run to make the changes (default does not rename)”<br /> end<br />

So when you run it, you will get output such as:

<br /> $ increment_migrations.rb 3<br /> Ignoring ‘.’<br /> Ignoring ‘..’<br /> Skipping ’001_create_people.rb’<br /> Skipping ’002_create_rejection_templates.rb’<br /> Converting ’003_create_users.rb’ to ’004_create_users.rb’<br /> Converting ’004_create_alive_statuses.rb’ to ’005_create_alive_statuses.rb’<br /> Converting ’005_create_contributors.rb’ to ’006_create_contributors.rb’<br />

Instructions

1. Cut and paste the file, or download it from increment_migrations.rb.
2. Save it somewhere
3. Make it executable chmod 755 /path/to/increment_migrations.rb
4. The change directory to ./db/migrations
5. then run /path/to/increment_migrations.rb 3
6. and if the output looks as expected
7. finally run /path/to/increment_migrations.rb 3 RUN

Finally, thanks to the client for permission to publish. Thanks for giving back to the community!

This entry was posted on Thursday, May 1st, 2008 at 6:45 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.