Course

Inspired and forked from opie

Course gives you a simple API for creating Operations using the Railsway oriented programming paradigm.

Usage

Simple Usage:

# Create an Operation for completing a Todo
class Todos::CompleteTodo < Course::Operation
  step :find_todo
  step :mark_as_complete

  def find_todo(todo_id)
    todo = Todo.find_by(id: todo_id)
    fail(:not_found, "Could not find the Todo using id: #{todo_id}") unless todo
    todo
  end

  def mark_as_complete(todo)
    success = todo.update(completed_at: Time.zone.now)
    fail(:update) unless success
    todo
  end
end

class TodosController < ApplicationController
  def complete
    # invoke the operation
    result = Todos::CompleteTodo.(params[:id])
    if result.success? # if #success?
      render status: :created, json: result.output # use output
    else
      render status: :bad_request, json: { error: error_message(result.failure) } # otherwise use #failure
    end
  end

  private

  def error_message(failure)
    case failure[:type]
      when :not_found then failure[:data]
      when :update then 'We were unable to make the changes to your todo'
      else 'There was an unexpected error, sorry for the inconvenience'
    end
  end
end

API

The Course::Operation API:

• ::step(Symbol) -> void indicates a method that is executed in the operation sequence
• #success? -> Boolean indicates whether the operation was successful
• #failure? -> Boolean indicates whether the operation was a failure
• #failure -> Hash | nil the erorr if the operation is a failure?, nil when it's a success
• #failures -> Array<Hash> | nil an array with all errors
• #output -> * if succcessful, it returns the operation final output validation error

Internal API:

• #fail(error_type: Symbol, error_data: *) -> Hash

Tentative API

• ::step(Array<Symbol>) -> void a series of methods to be called in parallel
• ::step(Course::Step) -> void an enforcer of a step signature which helps to compose other steps
• ::failure(Symbol) -> void indicates the method that handles failures

Installation

Add this line to your application's Gemfile:

gem 'course'

And then execute:

$ bundle

Or install it yourself as:

$ gem install course

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test 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.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/zhulik/course

License

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