Blog Post: The interactor design pattern

users_controller.rb

class UsersController < ApplicationController
  def create
    # Validate the form data and return if it is not correct
    # We'll come back and fill in the ???? with the call to the
    # interactor shortly. 
    unless (????)
      flash[:error] = ????
      redirect_to(new_users_path)
      return
    end
    
    user = User.create!(user_params)
    flash[:success] = "Woohoo, you created an account"
    
    redirect_to(user_path(@ser))
  end
  
  private
  
  def user_params
    @user_params || = params.require(:user).permit(
      :first_name,
      :last_name,
      :email
     )
  end
end

users_controller_1.rb

class UsersController < ApplicationController
  def create
    validator = UsersCreateActionInteractor.call(params: user_params)
    
    unless validator.success?
      flash[:error] = validator.err_msg
      redirect_to(new_users_path)
      return
    end
    
    user = User.create!(user_params)
    flash[:success] = "Woohoo, you created an account"
    
    redirect_to(user_path(@ser))
  end
  
  private
  
  def user_params
    @user_params || = params.require(:user).permit(
      :first_name,
      :last_name,
      :email
     )
  end
end

users_create_action_interactor.rb

class UsersCreateActionInteractor
  include Interactor

  def call
    @params = context.params

    case
    when name_is_blank?         then handle_blank_name
    when email_is_blank?        then handle_blank_email
    when email_is_taken?        then handle_email_is_taken
    when email_format_invalid?  then handle_email_format_invalid
    else
      handle_success
    end
  end

  private

  def name_is_blank?
    @params[:first_name].blank? || @params[:last_name].blank?
  end

  def handle_blank_name
    # Note: The interactor gem supports a short-hand notation for
    # the below actions:
    #    > context.fail!(err_msg: "...")
    context.err_msg = "Please fill in a name"
    context.fail!
  end

  def email_is_blank?
    @params[:email].blank?
  end

  def handle_blank_email
    context.err_msg = "Please fill in an email"
    context.fail!
  end

  def email_is_taken?
    User.find_by_email(@params[:email]).any?
  end

  def handle_email_is_taken
    context.err_msg = "That email already exists!"
    context.fail!
  end

  def email_format_invalid?
    (@params[:email] =~ /.*@.*\..*/i).blank?
  end

  def handle_email_format_invalid
    context.err_msg = "Sorry, that doesn't look like an email address"
    context.fail!
  end

  def handle_success
    # n/a
  end
end

http://abhchand.me/blog/?p=117