Threaded Comments

forum_model.py

class Topic(BaseModel):
    author = db.ReferenceProperty(User, required=True, collection_name='topics')
    title = db.StringProperty()
    body = db.TextProperty()
    
    @classmethod
    def topics(cls):
        topics = cls.all().order('-updated').fetch(100)
        prefetch_refprop(topics, cls.author)
        return topics
    
    def replies(self):
        """Fetches the topic's comments & sets each comment's 'replies' attribute"""
        keys = {}
        comments = self.comment_set.order('-created').fetch(1000)
        for comment in comments:
            keys[str(comment.key())] = comment
            comment.replies = []
        for comment in comments:
            parent_key = Comment.reply_to.get_value_for_datastore(comment)
            parent = keys.get(str(parent_key))
            if parent:
                parent.replies.append(comment)
        replies = [c for c in comments if not c.reply_to]
        prefetch_refprop(replies, Comment.author)
        return replies


class Comment(BaseModel):
    author = db.ReferenceProperty(User, required=True, collection_name='comments')
    topic = db.ReferenceProperty(required=True)
    reply_to = db.SelfReferenceProperty(collection_name='reply_to_set')
    body = db.TextProperty()


### views.py ###

class Video(BaseHandler):
    def get(self, id):
        ...
        
    def render_comments(self, comments):
        return self.render_string('_comment.html', comments=comments)


### _comment.html ###
{% for comment in comments %}
    <div class="comment">
        <p class="info">
            by {{ comment.author }}            
            {{ relative_date(comment.created) }}
        </p>
        {{ escape(comment.text) }}
        <a data-id="{{ comment.id }}" class="reply">reply</a>
        {{ handler.render_comments(comment.replies) }}
    </div>
{% end %}


### thread.html ###
<form id="reply_box" action="" method="post">
        {{ xsrf_form_html() }}
        <input type="hidden" name="action" value="comment">
        <label for="author">Author</label>
        <input id="author" type="text" name="author" tabindex="1">
        <label for="text">Text</label>
        <textarea id="text" name="text" tabindex="2"></textarea>
        <input type="submit" value="Post" tabindex="3">
    </form>
    {{ handler.render_comments(replies) }}