How to dynamically import_module from a relative path with python importlib

Question

My folder structure looks like:

__init__.py
core/
    fields.py
    managers.py
    models.py
    __init__.py
models/
    products.py
    suppliers.py
    __init__.py

From class A in fields.py I'm trying to load class Supplier using importlib.load_module from which is defined in products.py or suppliers.py. This is needed to populate some configurations in order to generate some sql.

The approach below generates TypeError: the 'package' argument is required to perform a relative import for '..models.suppliers.Supplier''. I'm not sure how to define the package, as this isn't an installed package.

import importlib

model_name = "Supplier"
path = f"...models.{model_name.lower()}s.{model_name}"
model = importlib.import_module(path)

To try and resolve this I've tried out various combination of something like below to no avail. Error ModuleNotFoundError: No module named '.core' or ModuleNotFoundError: No module named '.models' depending on the combination of .. I'm using.

import importlib

model_name = "Supplier"
path = f"...models.{model_name.lower()}s.{model_name}"
model = importlib.import_module(path, package=".core.fields")

path = f"{model_name.lower()}s"
model = importlib.import_module(path, package="..models")

Doesnt work either - but plainly importing from ..models import Supplier does.

I've also tried to get python to use the absolute path. But by using this approach, the error becomes: ImportError: attempted relative import with no known parent package (Referring to the imports in suppliers.py).

In such case it seems to fail on the relative imports used in suppliers.py. See below example.

from importlib.machinery import SourceFileLoader
from pathlib import Path
import os

model_name = "Supplier"
parent_path = Path(__file__).resolve().parent.parent
module_path = os.path.join(parent_path, 'models', f'{model_name.lower()}s.py')
Model = getattr(SourceFileLoader(model, module_path).load_module(), model_name)

EDIT: For completeness, throws ModuleNotFoundError: No module named '.'. So also a no go.

model = __import__(f"..models.{model.lower()}.{model}")

What am I missing?

Answer 1

After some more reading, turn out à solution was staring me right in the face.

Instead of trying to do funny things with importlib you can use getattr

def find_my_class(class_name):
    from .. import models as configuration_models

    module = getattr(configuration_models, f"{class_name.lower()}s")
    return getattr(module, class_name)