1. 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('/comment/', methods=['POST'])@loginFirstdef 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))

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

@app.route('/comment/', methods=['POST'])@loginFirst