json.author do
  json.partial! 'users/user', user: discuss.user
end
json.id discuss.id
json.content content_safe(discuss.content)
json.time time_from_now(discuss.created_at)
json.hack_id discuss.dis_id
json.hidden discuss.hidden
# 主贴和回复有一些不同点
if discuss.parent_id
  json.can_delete discuss.can_deleted?(current_user)
else
  json.praise_count discuss.praises_count
  json.user_praise discuss.praise_treads.select{|pt| pt.user_id == current_user.id}.length > 0
  json.can_delete discuss.can_deleted?(current_user) && child.count == 0
end