json.data do
  json.array! @follow_ups do |d|
    json.id d.id
    json.clazz d.clazz.name
    json.stage d.stage.name
    json.staff d.staff.user.real_name
    json.description d.description
    json.advise d.advise
    json.school d.business.department.school.name
    json.school_id d.business.department.school.id
    json.created_at d.created_at.to_s
    json.business d.business.name
    json.business_id d.business.id
    # teacher_ids = d.key_person.pluck(:teacher_id)
    json.tel d.key_person.pluck(:tel).select { |d| d.present?  }.join("、")
    json.key_people d.key_person.map { |d| d.teacher.name }.join("、")# key_people(teacher_ids)

  end
end

json.code 0
json.count @follow_ups.total_count