Unless all you ever need is triggers this gem is obsoleted with the release of https://github.com/neongrau/rails_db_objects where you can manage not only triggers but also views, functions, stored procedures, assemblies or basically do anything with plain custom SQL that does not fit into regular migrations.

Manage db triggers in Rails

Exactly like Yacine's gem for managing views, this gem will handle creating and dropping triggers that reside in /db/triggers/*.sql files. The name part of the .sql file will serve as the trigger name. Whenever rake db:migrate or rake db:rollback is called all triggers will be dropped and (re-)created afterwards. To delete a trigger just save the .sql file empty and it will be deleted next time you run migrations and be skippedduring trigger creation.

Just add rails_db_triggers to your Gemfile:

gem 'rails_db_triggers'

You can add/remove new paths in the initializers of Rails:

Rails.configure do |config|
  config.rails_db_triggers[:triggers_path] += %w( /some/view/path ) # defaults to /db/triggers
  config.rails_db_triggers[:triggers_ext] = "*.dbtrigger" #Using custom extensions to override default ".sql" extension.
  config.rails_db_triggers[:triggers_dbschema] = [] # if you don't need prefixes - defaults to ['dbo']
end

MIT

Ralf.