SimpleCommand

A simple, standardized way to build and use Service Objects (aka Commands) in Ruby

Requirements

• Ruby 2.0+

Installation

Add this line to your application's Gemfile:

gem 'simple_command'

And then execute:

$ bundle

Or install it yourself as:

$ gem install simple_command

Usage

Here's a basic example of a command that authenticates a user

# define a command class
class AuthenticateUser
  # put SimpleCommand before the class' ancestors chain
  prepend SimpleCommand
  include ActiveModel::Validations

optional, initialize the command with some arguments
  def initialize(email, password)
    @email = email
    @password = password
  end
mandatory: define a #call method. its return value will be available
through #result
  def call
    if user = User.find_by(email: @email)&.authenticate(@password)
      return user
    else
      errors.add(:base, :failure)
    end
    nil
  end
end

in your locale file ```yaml

config/locales/en.yml

en: activemodel: errors: models: authenticate_user: failure: Wrong email or password ```

Then, in your controller:

class SessionsController < ApplicationController
  def create
    # initialize and execute the command
    # NOTE: `.call` is a shortcut for `.new(args).call`
    command = AuthenticateUser.call(session_params[:email], session_params[:password])

# check command outcome
if command.success?
  # command#result will contain the user instance, if found
  session[:user_token] = command.result.secret_token
  redirect_to root_path
else
  flash.now[:alert] = t(command.errors.full_messages.to_sentence)
  render :new
end
  end
  private
  def session_params
    params.require(:session).permit(:email, :password)
  end
end

Test with Rspec

Make the spec file

spec/commands/authenticate_user_spec.rb

describe AuthenticateUser do
  subject(:context) { described_class.call(username, password) }

  describe '.call' do
    context 'when the context is successful' do
      let(:username) { 'correct_user' }
      let(:password) { 'correct_password' }
  it 'succeeds' do
    expect(context).to be_success
  end
end

context 'when the context is not successful' do
  let(:username) { 'wrong_user' }
  let(:password) { 'wrong_password' }

  it 'fails' do
    expect(context).to be_failure
  end
end
  end
end

Contributing

1. Fork it ( https://github.com/nebulab/simple_command/fork )
2. Create your feature branch (

   git checkout -b my-new-feature

   )
3. Commit your changes (

   git commit -am 'Add some feature'

   )
4. Push to the branch (

   git push origin my-new-feature

   )
5. Create a new Pull Request