credit_courses_controller.rb

# frozen_string_literal: true

module ContinuingEducation
  class CreditCoursesController < ApplicationController
    rescue_from ActiveRecord::RecordNotFound do |_|
      redirect_to 'https://precisionnutrition.com'
    end

    skip_authorization_check

    def index
      @credit_courses = ContinuingEducation::RecertificationCreditCoursePresenter.where(external: true).group_by(&:external_organization)
    end
  end
end

app/presenters/continuing_education/recertification_course_presenter.rb

module ContinuingEducation
  class RecertificationCreditCoursePresenter < RecertificationCreditCourse
    def foo
      name
    end
  end
end















module ContinuingEducation
  class CreditCoursesController < ApplicationController
    rescue_from ActiveRecord::RecordNotFound do |_|
      redirect_to 'https://precisionnutrition.com'
    end

    skip_authorization_check

    def index
      credit_courses = RecertificationCreditCoursePresenter.where(external: true) #.group_by(&:external_organization)

      @courses = credit_courses.map {|c| RecertificationCreditCoursePresenter.new(c) }.group_by(&:external_organization)

    end
  end
end

module ContinuingEducation
  class RecertificationCreditCoursePresenter
    attr_reader :course

    def initialize(course)
      @course = course
    end

    def foo
      course.name
    end

    def external_organization
      course.external_organization
    end
  end
end

<% if @courses.a.empty? %>

<% else %>

<% end %>