Flask AttributeError: module 'app' has no attribute 'run'

Question

My Flask project is structured as follows:

my_project
│
├── app
│   ├── __init__.py
│   ├── api
│   ├── static
│   └── templates
├── config.py
└── run.py

app/__init__.py:

from flask import Flask

app = Flask(__name__)

app.config.from_object('config')

run.py

from app import app

app.run(
    host=app.config.get('HOST', '0.0.0.0'),
    port=app.config.get('PORT', 5000)
)

This worked before, but I'm trying to migrate my project from Python 2 to Python 3, and running python run.py no longer works. I get the following error:

Traceback (most recent call last):
  File "/Users/rasmi/Projects/my_project/run.py", line 3, in <module>
    app.run(
AttributeError: module 'app' has no attribute 'run'

If I change the import style in run.py to match the one here:

from .app import app

app.run(
    host=app.config.get('HOST', '0.0.0.0'),
    port=app.config.get('PORT', 5000)
)

I get a different error:

Traceback (most recent call last):
  File "/Users/rasmi/Projects/my_project/run.py", line 1, in <module>
    from .app import app
ModuleNotFoundError: No module named '__main__.app'; '__main__' is not a package

Wrapping my app.run() call in an if __name__ == '__main__': block yields the same results. What's causing this issue?

Solution 1

I fixed this issue by renaming the app directory to something else (e.g. webapp). Using from webapp import app does the trick. This seems to be because package directory names take precedence over module names when importing. Perhaps using __path__ would allow one to get around this.

Solution 2

I solved this issue by doing this in my runserver.py:

from WebApp import app 
app.app.run(debug=True)

Where the name of the package is Webapp. Noticed how I used app twice. Also, my Flask app is called app.

├── WebApp
│   ├── app.py
│   ├── authentication.py
│   ├── __init__.py
│   ├── models.py
├── runserver.py

Solution 3

I was facing same issue for below line in my app,

import app.main.constant.constants as Constants

but then I restructure above command to below, and It worked for me.

from app.main.constant import constants as Constants