Import library from nested folder in Python 3

Question

I have code structured like this, where the some_lib is supposed to be installed with pip/setuptools

mainApp.py
submodule
 |some_lib
 |__init__.py
 |some_lib.py
 |helpers
 |helpers.py

and I want to import the some_lib.py from mainApp.py.

I can do easily if I have structure like this:

mainApp.py
some_lib
 |__init__.py
 |some_lib.py
 |helpers
 |helpers.py

however my goal is to have this library to be added as a submodule, and be able override the one installed in the system.

The issue is that the some_lib wants to import things like this: from some_lib.helper import SomeStuff, which leads to the library installed in the system with pip, since my package is submodule.some_lib.helper

I can workaround it with adding the library location to the search path with

import sys
sys.path.insert(0, my_lib_location)

but this doesn't seem correct to me, and I think will lead to issues later. I'd like to know if there's other way to do it, without touching the search paths. Also, I want to keep this compatible with other versions, and be installed, so I want to avoid modyfing the the imports in the library.

Answer 1

You need to add an __init__.py in the same level of the submodule and import the lib in that. You can also leave the __init__.py inside the some_lib empty,

mainApp.py
 |__init__.py
 |submodule
 |some_lib
 |__init__.py
 |some_lib.py
 |helpers
 |helpers.py

This is the repository link for template multi level python package.

• Rychu: I've realized I messed the stucture, I've edited to the correct one. I did try that, and no success, fails with ModuleNotFoundError: No module named 'some_lib' when the lib tries to import with some_lib
• Maryam Bahrami: @Rychu I dont know how do you import the some_lib in the outer init. You should import it like that: from .some_lib import [a function in the some_lib]. Do you do the same thing?
• Rychu: Hi, sorry for late response. The issue was that the lib itself assumed it's on the top level search path, and has non-relative imports inside. I did want to avoid both meddling with the search paths and modyfying the lib, but I guess the answer is 'no, there's no way to do, just that pick either one of the mentioned solutions'.
• Rychu: and just to be clear - I did try that import, but it did not solve my problem, but it's quite likely that I don't understand something about the python imports. For now I have used a workaround, but I'll try to check in isolation if I can get this to work with your suggestions, I'll mark the answer as a solution.
• Maryam Bahrami: @Rychu Sorry for late answer. I have created a template multi level python package, because I think it is tricky and without template it is difficult to start with. I have update the answer with the repo link. Feel free to make changes in the repo, add files or function. We can fix this together.