模型分离（选做）

模型分离--让代码更方便管理

新建models.py，将模型定义全部放到这个独立的文件中。

新建exts.py，将db = SQLAlchemy()的定义放到这个独立的文件中。

models.py和主py文件，都从exts.py中导入db。

在主py文件中，对db进行始化，db.init_app(app)。

主py

from flask import Flask,render_template,request,redirect,url_for,session
import config
from functools import wraps
from sqlalchemy import or_
from models import Question,User,Comment
from exts import db

app = Flask(__name__)
app.config.from_object("config")
db.init_app(app)

models.py

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

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)
    nickname = db.Column(db.String(20))

    @property
    def password(self):
        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)
        return result

class Question(db.Model):
    __tablename__="question"
    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"))
    author = db.relationship("User",backref=db.backref('question'))

class Comment(db.Model):
    __tablename__ = "comment"
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    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"))
    question_id=db.Column(db.Integer,db.ForeignKey("question.id"))
    author = db.relationship("User", backref=db.backref('comment'))
    question = db.relationship("Question",backref=db.backref("comment",order_by=create_time.desc))

exts.py

from flask_sqlalchemy import SQLAlchemy
db=SQLAlchemy()