Fastapi: [QUESTION] Postgresql template migration error

[laith43d]

Hi,

I am getting an issue when I want to use Alembic for migration. the error is as follows:

alembic current
Traceback (most recent call last):
  File "/home/lzah/.local/share/virtualenvs/app-211hAVC5/bin/alembic", line 10, in <module>
    sys.exit(main())
  File "/home/lzah/.local/share/virtualenvs/app-211hAVC5/lib/python3.7/site-packages/alembic/config.py", line 540, in main
    CommandLine(prog=prog).main(argv=argv)
  File "/home/lzah/.local/share/virtualenvs/app-211hAVC5/lib/python3.7/site-packages/alembic/config.py", line 534, in main
    self.run_cmd(cfg, options)
  File "/home/lzah/.local/share/virtualenvs/app-211hAVC5/lib/python3.7/site-packages/alembic/config.py", line 514, in run_cmd
    **dict((k, getattr(options, k, None)) for k in kwarg)
  File "/home/lzah/.local/share/virtualenvs/app-211hAVC5/lib/python3.7/site-packages/alembic/command.py", line 493, in current
    script.run_env()
  File "/home/lzah/.local/share/virtualenvs/app-211hAVC5/lib/python3.7/site-packages/alembic/script/base.py", line 475, in run_env
    util.load_python_file(self.dir, "env.py")
  File "/home/lzah/.local/share/virtualenvs/app-211hAVC5/lib/python3.7/site-packages/alembic/util/pyfiles.py", line 90, in load_python_file
    module = load_module_py(module_id, path)
  File "/home/lzah/.local/share/virtualenvs/app-211hAVC5/lib/python3.7/site-packages/alembic/util/compat.py", line 156, in load_module_py
    spec.loader.exec_module(module)
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "alembic/env.py", line 11, in <module>
    from app.db.base import Base 
ModuleNotFoundError: No module named 'app'

I tried many different scenarios, yet nothing worked.

[euri10]

it's very hard to respond such a question without a project layout and / or your PYTHONPATH and from where you're running your migrations, because it's all this is about.

having said that I recently pushed something very rough that does a alembic upgrade

just to explain its inner workings (and be sure you can handle things differently of course) the basic layout is:

├── app
│   ├── alembic.ini
│   ├── __init__.py
│   ├── main.py
│   ├── migrations
│   │   ├── env.py
│   │   ├── __init__.py
│   │   ├── README
│   │   ├── script.py.mako
│   │   └── versions
│   │   ├── 5200594f17bc_.py
│   ├── models
│   │   └── __init__.py
│   └── settings.py
└── prestart.sh

1. the alembic upgrade is ran in prestart.sh with PYTHONPATH=. alembic upgrade head
2. insideenv.py I setup the sqlalchemy.url with the following lines: https://github.com/euri10/euri10_fastapi_base/blob/033667640920cb69733e9c751f807c530a763816/python3.7-alpine3.8/app/migrations/env.py#L25-L30
   Note that env.py is one level below settings.py yet running with PYTHONPATH=. does the trick...

Hope it helps

edit: where is the FastAPI question :grin: ?

[laith43d]

Hey,
Thanks for your reply.

It is actually related to FastAPI because I am trying to use Alembic with the Postgresql template. PYTHONPATH=. worked fine.

I just run every command by putting PYTHONPATH=. in the beginning like so:

PYTHONPATH=. alembic current

or simply set the PYTHONPATH environment variable to be . :)

Best regards,

[tiangolo]

Thanks for your help @euri10 !

@laith43d it seems you are using the project generator, right? You should have a README.md in your project with details about these steps: https://github.com/tiangolo/full-stack-fastapi-postgresql/tree/master/%7B%7Bcookiecutter.project_slug%7D%7D#migrations

It seems like you were running your migrations locally, not inside Docker.

Anyway, I'm glad you solved your problem. Thanks for reporting back and closing the issue.