trustieforge/app/models/course_activity.rb

class CourseActivity < ActiveRecord::Base
  attr_accessible :user_id, :course_act_id,:course_act_type,:course_id
  # 虚拟关联
  belongs_to :course_act ,:polymorphic => true
  belongs_to :course
  belongs_to :user
  has_many :user_acts, :class_name => 'UserAcivity',:as =>:act
  after_create :add_course_lead,:add_user_activity, :add_org_activity, :update_cache_add
  before_destroy :destroy_user_activity, :destroy_org_activity, :update_cache_delete
  after_destroy :update_cache_delete_ex

  #在个人动态里面增加当前动态
  def add_user_activity
    user_activity = UserActivity.where("act_type = '#{self.course_act_type.to_s}' and act_id = '#{self.course_act_id}'").first
    if user_activity
      user_activity.save
    else
      if self.course_act_type == 'Message' && !self.course_act.parent_id.nil?
        user_activity = UserActivity.where("act_type = 'Message' and act_id = #{self.course_act.parent.id}").first
        user_activity.created_at = self.created_at
        user_activity.save
      else
        user_activity = UserActivity.new
        user_activity.act_id = self.course_act_id
        user_activity.act_type = self.course_act_type
        user_activity.container_type = "Course"
        user_activity.container_id = self.course_id
        user_activity.user_id = self.user_id
        user_activity.save
      end
    end
  end

  def add_org_activity
    org_activity = OrgActivity.where("org_act_type = '#{self.course_act_type.to_s}' and org_act_id = '#{self.course_act_id}'").first
    if org_activity
      org_activity.updated_at = self.updated_at
      org_activity.save
    else
      if self.course_act_type == 'Message' && !self.course_act.parent_id.nil?
        org_activity = OrgActivity.where("org_act_type = 'Message' and org_act_id = #{self.course_act.parent.id}").first
        org_activity.created_at = self.created_at
        org_activity.updated_at = self.updated_at
        org_activity.save
      else
        OrgActivity.create(:user_id => self.user_id,
                       :org_act_id => self.course_act_id,
                       :org_act_type => self.course_act_type,
                       :container_id => self.course_id,
                       :container_type => 'Course',
                       :created_at => self.created_at,
                       :updated_at => self.updated_at)
        end
      end
  end

  def destroy_user_activity
    user_activity = UserActivity.where("act_type = '#{self.course_act_type.to_s}' and act_id = '#{self.course_act_id}'")
    user_activity.destroy_all
  end

  def destroy_org_activity
    org_activity = OrgActivity.where("org_act_type = '#{self.course_act_type.to_s}' and org_act_id = '#{self.course_act_id}'")
    org_activity.destroy_all
  end

  # 发布新课导语
  # 导语要放置在课程创建信息之后
  def add_course_lead
    # 避免空数据迁移报错问题
    if self.course_act_type == "Course" and Message.where("id=12440").any?
      lead_message = Message.find(12440)
      name = lead_message.subject
      content = lead_message.content
      # message的status状态为0为正常，为1表示创建课程时发送的message
      # author_id 默认为课程使者创建
      message = Message.create(:subject => name, :content => content, :board_id => self.course.boards.first.id, :author_id => 1 , :sticky => true, :status => true )
      # 更新的目的是为了排序，因为该条动态的时间可能与课程创建的动态创建时间一致
      message.course_acts.first.update_attribute(:updated_at, message.course_acts.first.updated_at + 1) if message.course_acts.first
    end
  end

  #更新班级的动态缓存
  def update_cache_add
    CourseCache.update_course_acts_nums_cache(self.course.id,self,0)
    CourseCache.update_course_act_updated_at_cache(self.course.id)
  end

  #删除前更新
  def update_cache_delete
    CourseCache.update_course_acts_nums_cache(self.course.id,self,1)
    CourseCache.update_course_act_updated_at_cache(self.course.id)
  end

  #删除后更新
  def update_cache_delete_ex
    CourseCache.update_course_act_updated_at_cache(self.course.id)
  end

end