SafeMigrations

G'day, mate! Welcome to SafeMigrations, a ripper of a gem that makes your Rails migrations as safe as a kangaroo in the outback. With safe_ prefixed methods, this gem ensures your database schema changes are idempotent—no dramas if you run 'em twice. Built to play nice with Rails' CommandRecorder, it auto-reverses your migrations in the change method, so you can crack on with building your app without worrying about dodgy rollbacks.

Why SafeMigrations?

Tired of migrations chucking a wobbly when tables or columns already exist? SafeMigrations wraps Rails migration methods with safe_ prefixes (e.g., safe_create_table, safe_add_column) to check for existing schema elements before making changes. It hooks into Rails' CommandRecorder for automatic reversals in change-based migrations, keeping your database fair dinkum. Warning: Since it uses CommandRecorder, rollbacks may affect pre-existing schema elements—use with care or chuck in a reversible block for complex stuff.

Features

• Idempotent Migrations: safe_create_table, safe_add_column, safe_add_index, and more only run if needed.
• Auto-Reversal: Integrates with Rails' CommandRecorder to invert safe_ methods (e.g., safe_create_table → safe_drop_table) in change rollbacks.
• Rails 7.2+ Ready: Built for ActiveRecord 7.2, with support for modern Ruby 3.2.
• Aussie Spirit: Crafted with a bit of outback grit to keep your migrations smooth as a cold one on a summer arvo.

Installation

Add this line to your application's Gemfile:

gem 'safe_migrations'

Then give it a burl:

$ bundle install

Or install it yourself faster than a dingo nicks your lunch:

$ gem install safe_migrations

Usage

Use safe_ methods in your Rails migrations’ change block, and let Rails’ CommandRecorder handle the rollback. Here’s a cracking example:

class CreateUsers < ActiveRecord::Migration[7.2]
  def change
    safe_create_table(:users) do |t|
      t.string :name
      t.string :email
      t.timestamps
    end
    safe_add_column(:users, :role, :string, default: 'user')
    safe_add_index(:users, :email, unique: true)
  end
end

• Running: rails db:migrate creates the table, column, and index only if they don’t exist.
• Rolling Back: rails db:rollback inverts to safe_drop_table, safe_remove_column, safe_remove_index (in reverse order).
• Heads Up: If a table exists before the migration, safe_create_table skips it, but rollback may still call safe_drop_table. For critical cases, use reversible:

Development

No worries, mate! To get started:

1. Clone the repo and run bin/setup to install dependencies.
2. Run rake spec to give the tests a fair go.
3. Use bin/console for an interactive prompt to muck around with the code.

To install the gem locally:

$ bundle exec rake install

To release a new version:

1. Update the version in lib/safe_migrations/version.rb.
2. Run bundle exec rake release to tag the version, push to Git, and ship the gem to RubyGems.org.

Testing

The gem includes an RSpec suite to ensure your migrations are as solid as Uluru:

$ rake spec

Tests check idempotency (re-running migrations) and rollback behavior. Note the CommandRecorder limitation: pre-existing tables may get dropped on rollback. See spec/migration_spec.rb for details.

Contributing

Got a ripper idea or found a bug? Chuck us a pull request or bug report on GitHub at https://github.com/moskvin/safe_migrations. We’re keen as mustard to make this gem top-notch!

License

This gem is available as open-source under the terms of the MIT License.

Acknowledgements

Built with a nod to the Aussie spirit—because who doesn’t love a bit of fair dinkum coding? Cheers to the Rails community for the migration framework that makes this possible.

Crack on and make your migrations safe as, mate!