Cannot import var from top package

Question

This is my project structure:

myProject/
|
|-- src/
|   |-- services/
|   |   |-- __init__.py
|   |   |-- users.py
|   |   
|   |-- main.py
|   |-- ...
...

In main I have the mongo var that I need to use in users.py

# src/main.py

from flask import Flask
from flask_pymongo import PyMongo

import config
from services import api

app = Flask(__name__)

app.config["MONGO_URI"] = "mongodb://localhost:27017/myApp"
mongo = PyMongo(app)

api.init_app(app)


if __name__ == '__main__':
    app.run(host=config.HOST, port=config.PORT, debug=config.DEBUG)

in services init.py

# src/services/__init__.py
from flask_restx import Api
from .users import api as np_users
import config

api = Api(
    title=config.NAME,
    version=config.VERSION,
    description=config.DESCRIPTION,
)

api.add_namespace(np_users, path='/api/v1/users/users')

And I try to import mongo var in:

# src/services/users.py

     ...

from main import mongo

api = Namespace('users', description='users')
     ...

When I do:

python main.py

It throws me this error:

Traceback (most recent call last): File "main.py", line 7, in from services import api File "C:\myProject\src\services_init_.py", line 6, in from .users import api as ns_users File "C:\myProject\src\services\users.py", line 5, inices\users.py", line 5, in from main import mongo File "C:\myProject\src\main.py", line 7, in .py", line 7, in from services import api end_analisis_prediccion_equipos_b ImportError: cannot import name 'api' from 'services' (C:\myProject\src\services_init_.py)

Answer 1

To be able to import mongo from main (main.py) you have to set the value of mongo before importing the api from service. Your main.py should be like:

from flask import Flask
from flask_pymongo import PyMongo
import config
app = Flask(__name__)
app.config["MONGO_URI"] = "mongodb://localhost:27017/myApp"

mongo = PyMongo(app)

from services import api 

api.init_app(app)

if __name__ == '__main__':
    app.run(host=config.HOST, port=config.PORT, debug=config.DEBUG)

Although this will work, using this pattern (from main import ...) it's not a good practice. You can check some explanations here.