class IssueCache
  class<<self

    #-----------------------------讨论区帖子
    def issue_cache(id)
      key = "issue:"+id.to_s
      data = Rails.cache.read(key) rescue nil
      if data.nil?
        #直接存数据库对象
        data = Issue.find(id) rescue nil
        if data
          Rails.cache.write(key,data,{ expires_in: 90.minutes  }) rescue Rails.cache.delete(key)
        end
      end
      data
    end

    #更新
    def update_issue_cache(id,issue)
      key = "issue:"+id.to_s
      data = Rails.cache.read(key)
      if data.nil?
      else
        Rails.cache.write(key,issue,{ expires_in: 90.minutes  }) rescue Rails.cache.delete(key)
      end
    end

    #删除
    def delete_issue_cache(id)
      key = "issue:"+id.to_s
      Rails.cache.delete(key)
    end

  end
end