User create use case, validate, complete_date and save

user_create_use_case.rb

module UseCases
  module User
    module Create

      class Validate < RestMyCase::Base
        # all necessary validations to persit

        context_reader :user,
                       :user_attributes

        def perform
          context.user = user.present? ? user : User.new(user_attributes) # ActiveRecord Model

          if user_attributes

            if "#{user.first_name}".length == 0
              user.errors.add(:first_name, 'is missing')
            elsif "#{user.first_name}".length < 2
              user.errors.add(:first_name, 'is invalid, must have at least 2 characters')
            end

            if "#{user.last_name}".length == 0
              user.errors.add(:last_name, 'is missing')
            elsif "#{user.last_name}".length < 2
              user.errors.add(:last_name, 'is invalid, must have at least 2 characters')
            end

            ...
    
            if user.errors.length > 0
              # populate context.status with :confict,
              # context.status.conflict? = true and
              # stops execution flow
              failure!(:conflict) 
            end
          else
            failure!(:bad_request)
          end

        end
      end

      class CompleteData < RestMyCase::Base
        # use case to add more data before create

        context_reader :user # available since validate use case

        def perform
          user.object_token = 'generated_uniq_token'
        end
      end

      class Save < RestMyCase::Base
        # use case to save user

        context_reader :user

        def perform
          unless user.save
            failure!(:conflict)
          end
        end
      end

      class Base < RestMyCase::Base
        # create user use case

        depends Validate,
                CompleteData,
                Save
                
      end
      
    end
  end
end