我可以避免在 Flask 和 SQLAlchemy 中循环导入吗 [英] Can I avoid circular imports in Flask and SQLAlchemy

问题描述

app/init.py:

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
app = Flask(__ name __)
db = SQLAlchemy(app)  
from app import views, models

app/models.py:

app/models.py:

from app import db  # I want to avoid this everywhere

我真的不喜欢我的子模块依赖它们的父模块.也可以避免全局包变量吗?我想要一个更面向对象的解决方案.

I really don't like my submodules having a dependency on their parent. Also can the global package variables be avoided too? I want a more OO solution.

我认为应用程序的一种替代方法是使用蓝图，但随后我失去了路由装饰器.使用 SQLAlchemy 也不能对 db 做同样的事情(或者可以吗?).

One alternative for app is to use Blueprints I think, but then I loose the route decorator. Also the same cannot be done for db with SQLAlchemy (or can it?).

推荐答案

看看这个项目:https://github.com/sloria/cookiecutter-flask
这是以正确的方式做事的一个很好的例子.使用了许多很棒的 Flask 功能:蓝图、应用工厂等等.

这里是他们如何注册扩展，例如 SQLAlchemy 数据库:

Here is how they register extensions, such as SQLAlchemy Database:

# app/extensions.py
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()
...


# app/app.py
from app.extensions import db

def create_app(config_object=ProdConfig):
    app = Flask(__name__.split('.')[0])
    app.config.from_object(config_object)
    register_extensions(app)
    ...

def register_extensions(app):
    db.init_app(app)
    ...

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