Flask: cannot import name 'app'

Question

Trying to run my python file updater.py to SSH to a server and run some commands every few set intervals or so. I'm using APScheduler to run the function update_printer() from __init__.py. Initially I got a working outside of application context error but someone suggested that I just import app from __init__.py. However it isn't working out so well. I keep getting a cannot import name 'app' error.

app.py

from queue_app import app

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

__init__.py

from flask import Flask, render_template
from apscheduler.schedulers.background import BackgroundScheduler
from queue_app.updater import update_printer
app = Flask(__name__)
app.config.from_object('config')

@app.before_first_request
def init():
    sched = BackgroundScheduler()
    sched.start()
    sched.add_job(update_printer, 'interval', seconds=10)

@app.route('/')
def index():
    return render_template('index.html')

updater.py

import paramiko
import json
from queue_app import app

def update_printer():
    ssh = paramiko.SSHClient()
    ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    ssh.connect(app.config['SSH_SERVER'], username = app.config['SSH_USERNAME'], password = app.config['SSH_PASSWORD'])

...

File Structure

queue/
   app.py
   config.py
   queue_app/
      __init__.py
      updater.py

Error

Traceback (most recent call last):
  File "app.py", line 1, in <module>
    from queue_app import app
  File "/Users/name/queue/queue_app/__init__.py", line 3, in <module>
    from queue_app.updater import update_printer
  File "/Users/name/queue/queue_app/updater.py", line 3, in <module>
    from queue_app import app
ImportError: cannot import name 'app'

What do I need to do be able to get to the app.config from updater.py and avoid a "working outside of application context error" if ran from APScheduler?

Answer 1

当您在updater文件中导入__init__.py时，它是循环依赖项。在我的Flask设置中，app中创建了app.py。