Commands don't support alembic -x options

[ntvakou]

Hi, the current upgrade and downgrade commands don't support -x option, which is quite important for things like one off database migrations.

How do I extend command to support this? I can submit a patch if you're able to point me i the right direction

Is there a workaround to directly use alembic commands?

Thanks.

[miguelgrinberg]

You can use the alembic command directly. Have you tried that?

[ghost]

I tried doing just as you said with the alembic command, specifically with this alembic -c ./migrations/alembic.ini upgrade head but it keeps on giving me a RuntimeError: working outside of application context most likely due to env.py#L18

I found an implementation where instead of using this:

from flask import current_app
config.set_main_option('sqlalchemy.url', current_app.config.get('SQLALCHEMY_DATABASE_URI'))
target_metadata = current_app.extensions['migrate'].db.metadata

they used this ...

app = create_app()
config.set_main_option("sqlalchemy.url", app.config["SQLALCHEMY_DATABASE_URI"])
target_metadata = db.metadata

haven't tried it personally, but the way i see it, if i use their implementation, i'll probably break the old one, perhaps you have a better solution ??

[miguelgrinberg]

The reason Flask-Migrate can use current_app is that Flask-Script installs a request context before it calls commands. None of that exists under Alembic, obviously.

You can use this logic to make it work for both Flask-Migrate and native Alembic:

try:
    app = current_app._get_current_object()
except RuntimeError:
    app = create_app()
config.set_main_option("sqlalchemy.url", app.config["SQLALCHEMY_DATABASE_URI"])
target_metadata = db.metadata

[ghost]

Thanks for the great help, although i had to add some more code up top to make it work especially the importing of environment variables, ultimately i end up with the following code (for those that might be interested):

import os
import sys

...

# I honestly don't know what this thing do,
# but it let's you execute this file as if it's
# inside the app folder or something
sys.path.append(os.getcwd())

# look for the environment configuration file,
# if it exists, import them as environment variables
if os.path.exists('.env'):
    print('Importing environment from .env...')
    for line in open('.env'):
        var = line.strip().split('=')
        if len(var) == 2:
            os.environ[var[0]] = var[1]

...

from flask import current_app
from app import create_app, db

try:
    app = current_app._get_current_object()
except RuntimeError:
    app = create_app(os.getenv('FLASK_CONFIG') or 'default')

config.set_main_option("sqlalchemy.url", app.config["SQLALCHEMY_DATABASE_URI"])
target_metadata = db.metadata

the only flaw I can see here is with the importing of environment variable being executed twice when running inside the application context.

[miguelgrinberg]

You can move all that extra code that you added inside the except block, so that it only runs for the Alembic case.