Question

我正在尝试从 Instant Flask Web Development 一书中逐步学习Flask，但我得到了下面的错误。（这似乎是循环导入的问题。）问题是：

有人可以解释循环导入的修复和细节吗？

目录结构：

├── manage.py
├── requirements.txt
└── sched
    ├── __init__.py
    ├── __init__.pyc
    ├── app.py
    ├── app.pyc
    ├── static
    └── templates

manager.py：

from flask.ext.script import Manager
from sched import app

manager = Manager(app)
app.config['DEBUG'] = True

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

app.py：

from flask import Flask
app = Flask(__name__)

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

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

__init__.py 是安培。

命令行生成错误：

$ python manage.py runserver
Traceback (most recent call last):
  File "manage.py", line 8, in <module>
    app.config['DEBUG'] = True
AttributeError: 'module' object has no attribute 'config'

Answer 1

当你这样做时

from sched import app

您正在导入app模块。 app对象位于模块内。您要使用的导入是

from sched.app import app

Answer 2

替代架构：

# app.py:

from flask import Flask
app = Flask(__name__)
app.debug = True

from flask.ext.script import Manager
manager = Manager(app)

# __init__.py:

from .sched import app, manager
import sched.views # for your views
import sched.commands # for additional commands


# manager.py:

from sched import manager

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

 #views.py:

from .app import app

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

Answer 3

我建议您为自己的应用关注an app factory pattern。

manage.py
sched/
  __init__.py

在__init__.py中，您可以执行以下操作：

from flask import Flask
def create_app():
  app = Flask(__name__)
  app.config['DEBUG'] = True
  return app

manage.py

中的

from app import create_app
from flask.ext.script import Manager
app = create_app()
manager = Manager(app)
if __name__ == '__main__':
  manager.run()

这往往是大型应用程序结构的可扩展解决方案。

在Flask结构中未正确导入对象

3 个答案: