Detecting if app.py invoked via Flask Migrate

[diloreto]

Hi All,

Hopefully a simple question - I want to be able to run the Migrate function only when the app.py is being invoked by flask migrate. If we're running the app to start the server, no need to run any migrations. Any ideas/direction on how to do this?

For example:

# invoked by flask migrate means user called flask migrate -m "message" on the CLI
if( script_invoked_by_flask_migrate ):
    migrate = Migrate(app, db)
else:
    start_server()

Any help is appreciated!

[miguelgrinberg]

There's a chicken and egg problem. The flask migrate command is only registered when you create the Migrate instance.

[diloreto]

Thanks @miguelgrinberg - is there a canonical way to include the Migrate instantiation only for migrate needs (and not normal server deployment)? I tried inspecting the stack:

from inspect import stack

and using properties/functions of stack, but as you can imagine python sees no difference between:

flask run

and

flask migrate -m "message"

Any ideas?

[miguelgrinberg]

Why don't you use Alembic directly if you don't want to pollute your flask command with stuff?

[diloreto]

We actually ended up separating the app.py into app.py and migrate.py, and removed the Flask-Migrate code in app.py, and setting an env var on virtualenv starutp. Thank you!