模型分离（选做）

from exts import db
from werkzeug.security import generate_password_hash,check_password_hash
from datetime import datetime


# 创建用户模型
class User(db.Model):
    __tablename__ = ‘user‘
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    username = db.Column(db.String(20),nullable=False)
    _password = db.Column(db.String(200),nullable=False)#内部使用
    nickname=db.Column(db.String(50))

    @property
    def password(self): #外部使用
        return self._password

    @password.setter
    def password(self,row_password):
        self._password=generate_password_hash(row_password)

    def check_password(self,row_password):
        result=check_password_hash(self._password,row_password) #对比内部与外部存储的密码是否一样
        return result




#创建发布问答模型
class Question(db.Model):
    __tablename__ =‘questions‘
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    title=db.Column(db.String(100),nullable=False)
    detail=db.Column(db.Text,nullable=False)
    create_time=db.Column(db.DateTime,default=datetime.now)
    author_id=db.Column(db.Integer,db.ForeignKey(‘user.id‘))#外键约束，数据类型db.Integer第二个参数指定外键是user表的id
    author=db.relationship(‘User‘,backref=db.backref(‘questions‘))

# 创建评论模型
class Comment(db.Model):
    __tablename__ = ‘comments‘
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    author_id = db.Column(db.Integer, db.ForeignKey(‘user.id‘))
    questions_id = db.Column(db.Integer, db.ForeignKey(‘questions.id‘))
    create_time=db.Column(db.DateTime, default=datetime.now)
    detail=db.Column(db.Text,nullable=False)
    questions=db.relationship(‘Question‘,backref=db.backref(‘comments‘,order_by=create_time.desc))
    author=db.relationship(‘User‘,backref=db.backref(‘comments‘))

from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()

from exts import db

db.init_app(app)