完成评论功能

1. @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))

   <input type="hidden" name="question_id" value="{{ ques.id }}">

   class Comment(db.Model):
       __tablename__ = 'comment'
       id = db.Column(db.Integer, primary_key=True, autoincrement=True)
       author_id = db.Column(db.Integer, db.ForeignKey('user.id'))
       question_id = db.Column(db.Integer, db.ForeignKey('question.id'))
       creat_time = db.Column(db.DateTime, default=datetime.now)
       detail = db.Column(db.Text, nullable=False)
       question = db.relationship('Question', backref=db.backref('comments'))
       author = db.relationship('User', backref=db.backref('comments'))

   @login_re

   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