在我的简单flask应用程序中，我无法从型号.py. 循环导入？

Question

我正在尝试从我的型号.py，但我想我遇到了一个循环导入问题。我不知道怎么解决这个问题。你知道吗

我尝试过移动导入，并更改每个文件中的导入。你知道吗

你知道吗应用程序类型地址：

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
# import psycopg2
import os

# Init app
app = Flask(__name__)
basedir = os.path.abspath(os.path.dirname(__file__))


#SQLlite DATABASE
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///sleepTracker.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
app.config['DEBUG'] = True

# Init db
db = SQLAlchemy(app)

from models import SleepResult

@app.route('/')
def main():
    return 'Hello World!'

if __name__ == '__main__':
    app.run()

你知道吗型号.py地址：

from manage import db, app

class SleepResult(db.Model):
    __tablename__ = 'sleep_result'
    sleep_result_id = db.Column(db.Integer, primary_key=True)
    user_id = db.Column(db.Integer)
    sleep_result = db.Column(db.Integer)

    def __init__(self,user_id, sleep_result):
        self.user_id = user_id
        self.sleep_result = sleep_result

    def __repr__(self):
        return '<SleepTracker {}>'.format(self.sleep_result)

你知道吗管理.py地址：

from flask_script import Manager
from flask_migrate import Migrate, MigrateCommand

from app import app, db

migrate = Migrate(app, db)

manager = Manager(app)
manager.add_command('db', MigrateCommand)

if __name__ == '__main__':
    manager.run()

回溯：

Traceback (most recent call last):
  File "app.py", line 19, in <module>
    from models import SleepResult
  File "/home/john/Documents/sleep_tracker/models.py", line 1, in <module>
    from manage import db, app
  File "/home/john/Documents/sleep_tracker/manage.py", line 4, in <module>
    from app import app, db
  File "/home/john/Documents/sleep_tracker/app.py", line 19, in <module>
    from models import SleepResult
ImportError: cannot import name 'SleepResult'

Answer 1

你需要避免循环导入。在app.py中，为什么需要从模型中导入任何内容？你知道吗

# Init db
db = SQLAlchemy(app)

# Why do you need this here?
# from models import SleepResult

@app.route('/')
def main():
    return 'Hello World!'

if __name__ == '__main__':
    app.run()

如果最终需要在app.py中建模或需要处理其他循环导入，则通常可以将加载延迟到实际调用方法/函数之后。你知道吗

@app.route('/')
def main():
    """
    For example, if you need to reference SleepResult here...
    """
    from models import SleepResult


    return SleepResult.query.all()