mongo_id,target_id,target_type,unread
4d26212ccc8cb44df200001c,4d26212ccc8cb44df200001b,new_request,true
4d262132cc8cb44df200002c,4d262132cc8cb44df2000029,comment_on_post,true
4d262136cc8cb44df200003b,4d262136cc8cb44df200003a,new_request,true