old_contents: from db import session
  import model
  
  def to_json(post, user_id, last_visit=None, last_visit_filled=False):
  	if user_id:
  		if not last_visit_filled:
  			last_visit = session.query(model.ThreadVisit).\
  				filter(model.ThreadVisit.user == user_id, model.ThreadVisit.thread == post.thread, model.ThreadVisit.last_last_visit.isnot(None)).first()
  		is_new = True if not last_visit or last_visit.last_last_visit is None else last_visit.last_last_visit < post.published_at
  	else:
  		is_new = False
  
  	return {
  		'id': post.id,
  		'thread': post.thread,
  		'author': post.author,
  		'body': post.body,
  		'published_at': post.published_at.isoformat(),
  		'reaction': [ reaction.id for reaction in post.reactions ],
  		'is_new': is_new
  	}
  
new_contents: from db import session
  import model
  
  def to_json(post, user_id, last_visit=None, last_visit_filled=False):
  	if user_id:
  		if not last_visit_filled:
  			last_visit = session.query(model.ThreadVisit).\
  				filter(model.ThreadVisit.user == user_id, model.ThreadVisit.thread == post.thread, model.ThreadVisit.last_last_visit.isnot(None)).first()
  		is_new = True if (last_visit is None) or (last_visit.last_last_visit is None) else last_visit.last_last_visit < post.published_at
  	else:
  		is_new = False
  
  	return {
  		'id': post.id,
  		'thread': post.thread,
  		'author': post.author,
  		'body': post.body,
  		'published_at': post.published_at.isoformat(),
  		'reaction': [ reaction.id for reaction in post.reactions ],
  		'is_new': is_new
  	}
  
subject: Fix post NoneType error.