technoweenie / rails_migration_buddy

Migration Buddy
==============

Or, "the inevitable renumbering and conflict-resolution of miggy tardust"

This is a tool to help merge rails branches with conflicting migrations.  The basic
idea goes like this:

* First you migrate down to the migration you were at when you branched.
* Renumber any new migrations you created that conflict with any new migrations in
  the target branch.
* Commit the renames.
* Merge to the target branch (usually 'master').
* Migrate back up.

Wow, what a pain, right?  Instead, make sure your new branch has a clean working copy:

(These examples use the included example app)

  $ git checkout example
  $ rake git:rebase_migrations BRANCH=example MASTER=example
  (in /Users/rick/migration_buddy)
  No new migrations in "example"
  No new migrations in "example" either, you're clear!

If you have no new migrations, rock on!  (So what, that was a contrived example)

  $ git checkout posting-with-comments
  $ rake git:rebase_migrations MASTER=posting
  (in /Users/rick/migration_buddy)
  No new migrations in "posting"
  1 new migration(s) in "posting-with-comments": ["004_add_comments.rb"].
  You should 'rake db:migrate VERSION=3' before merging with "posting

There were no new migrations in the master branch, so no rebasing needed.  Notice
how it guessed the BRANCH var from the current branch.  It defaults MASTER to 'master',
but the plugin itself is in the example's master branch.

  $ git checkout posting
  $ rake git:rebase_migrations MASTER=example
  (in /Users/rick/migration_buddy)
  1 new migration(s) in "master": ["002_modify_users.rb"].
  2 new migration(s) in "posting": ["002_add_posts.rb", "003_make_posts_whatever.rb"].

  Suggested Renumbering...
  git mv db/migrate/002_add_posts.rb db/migrate/003_add_posts.rb
  git mv db/migrate/003_make_posts_whatever.rb db/migrate/004_make_posts_whatever.rb

  Run with RUN=1 to actually rename the files.

Finally, something interesting!  It suggests the 'git mv' commands for you, but doesn't 
actually do anything.

  $ rake git:rebase_migrations MASTER=example RUN=1
  (in /Users/rick/migration_buddy)
  1 new migration(s) in "example": ["002_modify_users.rb"].
  2 new migration(s) in "posting": ["002_add_posts.rb", "003_make_posts_whatever.rb"].

  Renumbering...
  git mv db/migrate/002_add_posts.rb db/migrate/003_add_posts.rb
  git mv db/migrate/003_make_posts_whatever.rb db/migrate/004_make_posts_whatever.rb

  Migrations rebased!  Next actions:
   rake db:migrate VERSION=1
   git commit -m '...'
   git checkout example
   git merge posting
   rake db:migrate

Don't forget to install the fancy grit gem:

  sudo gem install grit

License
=======

This is licensed under the WTFPL License

http://sam.zoy.org/wtfpl/

It'll probably be included in Rails.  Until then:

  http://github.com/technoweenie/rails_migration_buddy/tree

Happy rebasing!