environ variable not visible to flask app

Question

Flask app was not getting SQLALCHEMY_DATABASE_URI value from .env in order to create tables in ProstgreSQL db.

Here's config:

import os

class Config(object):
    DEBUG = False
    TESTING = False
    CSRF_ENABLED = True
    SECRET_KEY = os.environ.get('SECRET_KEY')
    SQLALCHEMY_DATABASE_URI = os.environ.get('SQLALCHEMY_DATABASE_URI')
    SQLALCHEMY_TRACK_MODIFICATIONS = False
...

I tried

>>> from app.extensions import db
>>> db.create_all()

and

>>> from app import create_app 
>>> app = create_app()
>>> from app.extensions import db
>>> db.create_all()

and

>>> from app import create_app
>>> app=create_app()
>>> app.app_context().push() 
>>> from app.extensions import db
>>> db.create_all()

With a little help from my friends on Stackoverflow, I got to the working proc:

>>> from dotenv import load_dotenv
>>> load_dotenv()
>>> import os
>>> os.getenv('SQLALCHEMY_DATABASE_URI')
>>> from app import create_app
>>> app = create_app()
>>> app.app_context().push()   
>>> from app.extensions import db
>>> db.create_all()

Question: Where is the bug? config.py has import os line. python_dotenv is installed. What shall I do to avoid using the first four lines in the proc above?

Any help is greatly appreciated.

Answer 1

Until load_dotenv(), whatever is in .env is ignored. The question is where to do that load_dotenv(). It has to happen before anyone reached in to os.environ expecting something from .env to be there.

The usually place, if you're following the pattern from the Flask Mega Tutorial, is right before

class Config(object):

E.g., https://github.com/miguelgrinberg/microblog/blob/v0.15/config.py