完成评论功能

1. 定义评论的视图函数
   @app.route('/comment/',methods=['POST'])
   def comment()：
   读取前端页面数据，保存到数据库中

   @app.route('/comment/', methods=['POST'])
   @loginFirst
   def comment():
       comment = request.form.get('new_comment')
       ques_id = request.form.get('question_id')
       author_id = User.query.filter(User.username == session.get('user')).first().id
       comm= Comment(author_id=author_id, question_id=ques_id, detail=comment)
       db.session.add(comm)
       db.session.commit()
       return redirect(url_for('detail', question_id=ques_id))

2. 用<input type="hidden" 方法获取前端的"question_id" 

   <ul class="list-group" style="margin:10px" >
            {% for foo in ques.comments %}
                  <li class="list-group-item"style="background-color:lightcyan;height:250px;width:600px;">
               <span class="glyphicon glyphicon-leaf" aria-hidden="true"></span>
               <a href="#">作者ID:{{ ques.author.username }}</a>
               <br>
               <a href="#">标题:{{ ques.title }}</a>
               <br>
               <p style="color:black">详情:{{ ques.detail }}</p>
               <p>评论:{{ foo.detail }}</p><br>
               <span class="badge"  style="margin-left: 60%">评论时间:{{ foo.create_time }}</span>
           </li>
        {% endfor %}
           </ul>

3. 显示评论次数

   <h5>评论：({{ ques.comments|length }})</h5>

4. 要求评论前登录
5. 尝试实现详情页面下的评论列表显示

   def loginFirst(func):
       @wraps(func)
       def wrapper(*args, **kwargs):
           if session.get('user'):
               return func(*args, **kwargs)
           else:
               return redirect(url_for('login2'))
   
       return wrapper