Question

我正在尝试从我的models.py导入一个类，但是我认为我遇到了循环导入问题。我不确定该如何解决。

我尝试移动导入，并更改每个文件中的导入。

app.py：

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()

models.py：

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)

manage.py：

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

您需要避免循环导入。在您的app.py中，为什么需要从模型中导入任何内容？

# 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()

如果最终需要使用app.py中的模型或需要解决其他循环导入问题，通常可以避免延迟加载，直到实际调用方法/函数为止。

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


    return SleepResult.query.all()

在我的简单Flask应用程序中，我无法从models.py导入类。循环进口？

1 个答案: