Sequins ✨

Sequins allows you to define temporal sequences of actions. A sequence is one or more steps that run in any order you choose with any delay between them you choose.

Add this line to your application's Gemfile:

gem 'sequins'

And then execute:

$ bundle

Or install it yourself as:

$ gem install sequins

A basic sequence class looks like this:

class ExampleSequence < Sequins::Base
  sequence do
    step :start, initial: true do
      ExampleMailer.example_message(target.id).deliver_later

      delay 3.days, then: :step_2
    end

    step :step2 do
      ExampleMailer.example_step_2(target.id).deliver_later
      end_sequence
    end
  end
end

A step is a Ruby block. It has the following attributes available:

• target is the target object that you pass into trigger or run_step_for_target
• step_name is the step that's currently running
• sequence is an instance of Sequins::Sequence. From this you have access to the sequence class via sequence.klass

You also have direct access to class methods on your Sequence::Base subclass. For example:

class Example2Sequence < Sequins::Base
  sequence do
    step :start, initial: true do
      send_message target, "hi there"
    end
  end

  def self.send_message(target, text)
    SomeMailer.send_message(target.id, text).deliver_later
  end
end

You can also send arguments to trigger or run_step_for_target which will be passed as block arguments. Example:

class Example3Sequence < Sequins::Base
  sequence do
    step :start, initial: true do |something|
      if something.present?
        delay 3.days, then: :next_step
      else
        end_sequence
      end
    end

    step :next_step do
      # something interesting
    end
  end
end

Example3Sequence.trigger(User.first, "this will trigger a delay")

The first argument to delay is always an interval, usually expressed as a number of days. Ex: 3.days. In addition, it can take these arguments:

• then (always required) this tells delay which step to run next
• at specifies a time relative to the target's local timezone to run the next step
• only limits what days to send on. Currently the only valid option is :weekdays

To trigger a sequence, call the trigger class method and pass in the target. For example, if we want to trigger the example sequence for Joel, we'd do this:

ExampleSequence.trigger(User.find_by(email: 'joel@egghead.io'))

Sequences can define hooks. The available hooks are:

before_each_step # runs before every step.
after_each_step  # runs after each step
before_sequence  # runs before the sequence starts. 
after_sequence   # runs after the sequence ends with an explicit `end_sequence`

Hooks are run in the same way steps are, so you have access to all of the same attributes as a step. Within before_each_step and after_each_step, step_name will be set to the step that is about to or just finished running. Within before_sequence and after_sequence step_name has no meaning.

# in config/initializers/sequins.rb

Sequins.configure do |config|
  # Specify the default time zone in tz format.
  # If you are using Sequins inside Rails this will be set to Rails.configuration.time_zone.
  # You can also change this per-target by providing a `local_time_zone` method on your target.
  config.default_time_zone = 'America/Chicago'
end

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/eggheadio/sequins. 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.

Copyright (c) Peter Keen. The gem is available as open source under the terms of the MIT License.

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