Pgtrigger

Create trigger for postgres using ActiveRecord migration

TODO:

• Create tests
• Create reversible method for create_trigger

Add this line to your application's Gemfile:

gem 'pgtrigger'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install pgtrigger

Create a migration like this

class AddTriggerToSomeTable < ActiveRecord::Migration[5.1]
  def up
    create_trigger(:table_name, :increase_order, before: [:insert, :update], declare: {var_1: "text := 'test'", var_2: :integer}) do
        <<-TRIGGERSQL
            var_2 := -1

            NEW."order" := (
              SELECT COALESCE(MAX("order"), 0) +1
              FROM table_name
            );

          RETURN NEW;
        TRIGGERSQL
    end
  end

  def down
    remove_trigger(:table_name, :increase_order)
  end
end

The create_trigger method, the first and second parameters are about table and name of trigger respectively. The third params can be hashes before: or after:, passing string or array to indicate what event this trigger it will be executed. The param declare: is used to declare variables

NOTE: Yet is necessary to specify the down method, otherwise the trigger cannot be removed when execute migration rollback.

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/pgtrigger. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

I appreciate new collaborators for this project.

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

Everyone interacting in the Pgtrigger project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.