How to import the own model into myproject/alembic/env.py?

Question

I want to use alembic revision --autogenerate with my own model classes. Because of that I need to import them in myproject/alembic/env.py as described in the docs. But this doesn't work even if I tried a lot of variations.

I am not sure in which context (don't know if this is the correct word) does alembic run the env.py. Maybe that causes some errors.

This is the directory and file structure I use.

myproject/     common/         __init__.py         model.py     alembic/         env.py 

The error is kind of that

    from .common import model SystemError: Parent module '' not loaded, cannot perform relative import 

myproject itself is just a repository/working directory. It is not installed into the system (with pip3, apt-get, easyinstall or anything else).

Answer 1

You can set the PYTHONPATH environment variable to control what python sees as the top level folder, eg. if you are in the root folder of your project:

PYTHONPATH=. alembic revision -m "..." 

Then you can use a "normal" import in your alembic env.py, relative to your root folder, in your example:

from src.models.base import Base 

Answer 2

Fiddling around few hours with this same issue, I found out a solution. First, this is my structure right now:

. ← That's the root directory of my project ├── alembic.ini ├── dev-requirements.txt ├── requirements.txt ├── runtime.txt ├── setup.cfg ├── src │   └── models │       ├── base.py │       ... │       └── migrations │           ├── env.py │           ├── README │           ├── script.py.mako │           └── versions │           └── tests 

in env.py I simply did this:

import sys from os.path import abspath, dirname sys.path.insert(0, dirname(dirname(dirname(abspath(__file__))))) # Insert <.>/src import models # now it can be imported target_metadata = models.base.Base.metadata 

Hope you find this useful! :)

EDIT: I then did my first revision with the database empty (with no tables yet), alembic filled everything automatically for upgrade() and downgrade(). I did that in this way because not all my tables were automagically detected by alembic.