关于评论树：

　　1、评论信息在数据库中是以列表形式记录，其中至少包括当前评论id、父评论id（根评论id为null）、和评论内容，

　　2、在显示评论时，首先数据库中调取评论信息列表，列表中的每个元素对应一条评论信息字典，

　　3、将评论信息字典创建成有结构的评论树字典：build_tree

　　4、将评论树字典转换成html样式：tree

import collections,json

# 将数据库中的普通字典列表，转换成有结构的评论树字典
def tree_search(comment_dic,comment_obj):
    for k,v_dic in comment_dic.items():
        if json.loads(k)['nid'] == comment_obj['father_id']:
            comment_dic[k][json.dumps(comment_obj)] = collections.OrderedDict()
            return
        else:
            tree_search(comment_dic[k],comment_obj)


def build_tree(comment_list):
    comment_dic = collections.OrderedDict()     #有序字典
    for comment_obj in comment_list:
        if comment_obj['father_id'] is 0:
            comment_dic[json.dumps(comment_obj)] = collections.OrderedDict()
        else:
            tree_search(comment_dic,comment_obj)
    return comment_dic

#--------------------------------------------------

# 将有结构的评论树字典转换成html样式
# 注意：评论的全部子评论用ul表示，且一条评论是一个li，每个li中含有一个span显示评论的具体内容

TEMP1 = """
    <li class="items" style='padding:8px 0 0 %spx;'>
        <span onclick="show_ul(this)"><a class="writer">%s:</a>%s<a class="time">--%s</a></span>
        <a class="reply" onclick="reply_comment(this,%s,%s)">回复</a>        
        <a class="reply" onclick="delete_comment(this,%s,%s)">删除</a>        
        <a class="reply">举报</a>        
"""


def generate_comment_html(sub_comment_dict,margin_left_val):
    html = "<ul class='hide'>"
    for k,v_dic in sub_comment_dict.items():
        key = json.loads(k)
        html += TEMP1 %(margin_left_val,key['writer'],key['content'],key['time'],key['nid'],key['news_id'],key['nid'],key['news_id'])
        if v_dic:
            html += generate_comment_html(v_dic,margin_left_val)
        html += "</li>"
    html += "</ul>"
    return html


def tree(comment_tree):
    html = ''
    for k,v in comment_tree.items():
        key = json.loads(k)
        html += TEMP1 %(0,key['writer'],key['content'],key['time'],key['nid'],key['news_id'],key['nid'],key['news_id'])
        html += generate_comment_html(v,16)
        html += "</li>"
        html += "<div class='xuxian'></div>"
    return html
comment-tree

　　

class AccountHandler(BaseHandler):
    def get(self):
        # 获取数据库中指定新闻的评论信息
        news_id = self.get_argument('news_id')
        comment_info = account_info().get(news_id)
        # print(comment_info)

        # 创建评论树
        comment_tree = build_tree(comment_info)
        # print(comment_tree)     # test

        # 将评论树转化成html样式
        comment_html = tree(comment_tree)
        # print(comment_html)  # test

        self.write(json.dumps(comment_html))

　　5、添加新评论时，要记录新评论的父评论id

　　6、删除评论时，连带子评论一起删除

class AccountDelHandler(BaseHandler):
    def __post_func(self,rep,post_info):
        # 检查comment_id是否是当前用户，
        if account_del().check_user(post_info['comment_id'],self.session['user']['user_id']):

            # 将所有待删除的评论id放入一个列表
            del_list = [int(post_info['comment_id']),]

            # 提取指定news_id的所有评论的nid、father_id
            ID_fatherID = account_del().id_father(post_info['news_id'])

            # 将所有待删除的子评论id放入列表
            for item in ID_fatherID:
                if item['father_id'] in del_list:
                    del_list.append(item['nid'])

            # 删除数据库中对应评论
            account_del().remove(del_list)

            rep.status = 1
        else:
            # 标识当前用户非评论发布者
            rep.data = 1

        return rep