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
2. 用<input type="hidden" 方法获取前端的"question_id" 
3. 显示评论次数
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

   @app.route('/detail/<question_id>')
   def detail(question_id):
       quest = Question.query.filter(Question.id == question_id).first()
       return render_template('detail.html',ques = quest)
   
   @app.route('/comment/',methods=['POST'])
   @loginFirst
   def comment():
       comment = request.form.get('new_comment')
       ques_id = request.form.get('question_id')
       auth_id = User.query.filter(User.username == session.get('user')).first().id
       comm = Comment(author_id = auth_id,question_id = ques_id,detail =comment)
       db.session.add(comm)
       db.session.commit()
       return redirect(url_for('detail',question_id = ques_id))
   
   
   
   
   if __name__ == '__main__':
       app.run(debug=True)
   

   　detail.html　

   {% extends 'base.html' %}
   {% block title %}问答详情{% endblock %}
   
   {% block head %}
   <link rel="stylesheet" href="{{ url_for('static',filename='css/question.css')}}">
   {% endblock %}
   
   {% block main %}
       <div class="page-header">
           <h3>{{ ques.title }}<br><small>{{ ques.author.username }}
               <span class="badge">{{ ques.creat_time }}</span>
               </small>
           </h3>
       </div>
       <p class="lead">详情 {{ ques.detail }}</p>
       <hr>
   
       <form action="{{ url_for('comment') }}" method="post" class="box">
       <div class="form-group">
           <textarea name="new_comment" class="form-control" rows="3" id="new_comment" placeholder="write your comment"></textarea>
           <input name="question_id" type="hidden" value="{{ ques.id }}" />
       </div>
       <button type="submit" class="btn btn-default">发送</button>
       </form>
       <h4>评论：({{ ques.comments|length }})</h4>
   
       <ul class="list-group" style="margin: 10px;list-style: none">
           {% for foo in ques.comments %}
               <li class="list-group-item">
                   <span class="glyphion glyphion-heart-empty" aria-hidden="true"></span>
                   <a href="#">{{ foo.author.username }}</a>
                   <span class="badge">{{ foo.creat_time }}</span>
                   <p style="width: 450px;"> 详情 {{ foo.detail }}</p>
   
               </li>
           {% endfor %}
       </ul>
   {% endblock %}