educoder/app/models/department.rb

class Department < ApplicationRecord
  belongs_to :school

  has_many :department_members, dependent: :destroy

  after_create_commit :reset_data_cache
  after_update_commit :reset_data_cache

  def self.cached_names_data(school)
    Rails.cache.fetch(names_data_cache_key(school.id), expires_in: 7.days) do
      school.departments.select(:id, :name).as_json
    end
  end

  private

  def reset_data_cache
    # 清除部门名称缓存
    if new_record? || name_previously_changed?
      Rails.cache.delete(self.class.names_data_cache_key(school_id))
    end
  end

  def self.names_data_cache_key(school_id)
    "schools/#{school_id}/department_names_data"
  end
end