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Renumber Clashing Rails Migrations in One Easy Step

If you work in a team on a Rails project, chances are that you and your team mates occasionally create identically-numbered migrations. Renumbering a migration that you’re working on is a pain, unless you’re using this handy renumber_migrations plugin.

Scenario

You’re working on migration 045_add_my_new_feature.rb, when one of your team-mates checks 045_some_other_migration.rb into svn. You notice the numbering clash (or rake db:migrate notices it for you), and you simply run the db:migrate:renumber task:

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% rake db:migrate:renumber

Voilá - your migration is renumbered to 046, and the database schema is left at version 044 ready for you to re-test your migration. (If you had multiple new migrations, all of them would get renumbered.)

Requirements and assumptions

To be able to use this plugin, you must:

  1. Be using subversion for your version control
  2. Have a working #down method for each local clashing migration
  3. Have network access to the subversion server, since clashing migrations are temporarily removed locally, and later re-requested.

Getting it

You can use script/plugin to install the plugin:

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% script/plugin install http://rails.sanityinc.com/plugins/renumber_migrations/

Alternatively, you can download a snapshot from the plugin’s git repository instead (tip: that page has an RSS feed for tracking check-ins). Unpack the snapshot tarball under your RAILS_ROOT/vendor/plugins directory.

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