Flask-分开Models解决循环引用

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 Flask
from flask_sqlalchemy import SQLAlchemy
from models import Article

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///./Article.db'
SQLALCHEMY_TRACK_MODIFICATIONS = False
db = SQLAlchemy(app)

# db.create_all()
@app.route('/')
def index():
    return 'index'

if __name__ == '__main__':
    #最好关闭debug
    app.run()

from app import db
class 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app
db = SQLAlchemy()

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

from flask import Flask
from models import Article

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///./Article.db'
SQLALCHEMY_TRACK_MODIFICATIONS = False
db.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 db
class 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)