json.courses @courses do |course|
  json.course_id course.id
  json.course_name course.name
  json.created_at course.created_at
end

json.stages @subject.stages.includes(shixuns: [user: :user_extension]) do |stage|
  index = 1
  json.shixuns stage.shixuns do |shixun|
    if shixun.status == 2 && !shixun.is_jupyter && @all_shixun_ids.include?(shixun.id)
      json.shixun_id shixun.id
      json.id shixun.id
      json.identifier shixun.identifier
      json.shixun_name "#{stage.position}-#{index} #{shixun.name}"
      json.title shixun.name
      json.level level_to_s(shixun.trainee)
      json.study_count shixun.myshixuns_count
      json.author_name shixun.user.real_name
      json.author_img url_to_avatar(shixun.user)
    end
    index += 1
  end
end