Service objects

service_base.rb

class ServiceBase

  attr_reader :model, :errors

  class AbstractMethodError < Exception
  end

  def initialize(model)
    @model = model
    @errors = []
  end

  %w(create update destroy).each do |name|
    define_method name do
      raise AbstractMethodError, I18n.t('exceptions.abstract')
    end
  end

  private

    # The presence of errors decide whether we will update a model or not.
    # If the final update fails, the service's errors are updated via our model and we return false.
    def update_model(params)
      false if @errors.any?
      if @model.update(params)
        true
      else
        @errors += @model.errors.full_messages
        false
      end
    end

end

user_service.rb

class UserService < ServiceBase

  def update(params)
    if params[:password].present?
      update_password(params[:current_password], params[:password], params[:password_confirmation])
    else
      update_model(params)
    end
  end

  def update_password(current_password, password, confirmation)
    @errors << I18n.t('services.user.errors.password.update') if @model.nil? || current_password.nil? || password.nil? || confirmation.nil?
    @errors << I18n.t('services.user.errors.password.match') if password != confirmation
    @errors << I18n.t('services.user.errors.password.current') unless @model.try(:authenticate, current_password)
    update_model({ password: password, password_confirmation: confirmation })
  end

end

users_controller.rb

class UsersController < ApplicationController
  
  def update
    respond_to do |format|
      @service = UserService.new(current_user)
      if @service.update(user_params)
        format.html { redirect_to my_path, notice: I18n.t('services.user.update') }
        format.json { render json: @service.model.to_json, status: :ok }
      else
        format.html { redirect_to my_path, notice: @service.errors }
        format.json { render json: { errors: @service.errors }, status: :unprocessable_entity }
      end
    end
  end
  
end