Flask-分开Models解决循环引用

在之前我们测试中,所有语句都在同一个文件中,但随着项目越来越大,管理起来有所不便,所以将Models分离.
基本的文件结构如下

\—–app.py
\—–models.py

from flask import Flaskfrom flask_sqlalchemy import SQLAlchemyfrom models import Articleapp = Flask(__name__)app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///./Article.db'SQLALCHEMY_TRACK_MODIFICATIONS = Falsedb = SQLAlchemy(app)# db.create_all()@app.route('/')def index():    return 'index'if __name__ == '__main__':    #最好关闭debug    app.run()

from app import dbclass Article(db.Model):    __tablename__='article'    id = db.Column(db.Integer,primary_key=True)    title = db.Column(db.String(100),nullable=False)    content = db.Column(db.Text,nullable=False)

但此时会出现循环引用的错误,也就是你需要我的,我需要你的,错误如下图

解决方法

新建一个exts.py文件
\—–app.py
\—–models.py
\—–exts.py

exts.py文件内容如下

from flask_sqlalchemy import SQLAlchemy#此时先不传入appdb = SQLAlchemy()

app.py更改如下
去掉from flask_sqlalchemy import SQLAlchemy
增加db.init_app(app)

from flask import Flaskfrom models import Articleapp = Flask(__name__)app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///./Article.db'SQLALCHEMY_TRACK_MODIFICATIONS = Falsedb.init_app(app)# db.create_all()@app.route('/')def index():    return 'index'if __name__ == '__main__':    #最好关闭debug    app.run()

models.py

from exts import dbclass Article(db.Model):    __tablename__='article'    id = db.Column(db.Integer,primary_key=True)    title = db.Column(db.String(100),nullable=False)    content = db.Column(db.Text,nullable=False)