relative import with no known parent package error while importing from different folder

Question

I've a directory structure like this below:

ParentPackage/
 childPackage/
    __init__.py
    subpackageOne/
        __init__.py
        moduleA.py
        moduleB.py
    test/
        __init__.py
        test.py

I'm trying to import a method "methodX" from moduleA.py to my test.py residing inside test folder. below is the code which I've tried

import os
import sys
sys.path.append(os.path.realpath('..'))
from ..subpackageOne.moduleAimport methodX

but getting error "ImportError: attempted relative import with no known parent package".

In addition to this moduleA.py is importing moduleB.py and while running the test I am getting No module named 'moduleB'.

There are already lot of question has been asked on this topic, however suggestions provided for those didn't work for me.

Answer 1

Based on your architecture, you can do that:

import os
import sys
# Assuming your package is on a drive called C:. 
# That is what I mean by absolute path, it needs to refer the path from the disk 
# so it does not depend on where you are
sys.path.append("C:/path/to/childPackage")
# Absolute import is just importing wihtout using dots at the beginning. 
# In this case, python will look for installed packages in your environment
# and then any folder that is in your path.
from subpackageOne.moduleA import methodX

If you prefer, you may want to add the parentPackage in your path so you can use any childPackage in case you have several.

sys.path.append("C:/path/to/parentPackage")

from childPackage.subpackageOne.moduleA import methodX

Note: I see you have __init__ files in your architecture which suggests you may want to create an installable package that you can build after (using a setup.py or setup.cfg file). In this case, you could install your package in your virtual environment and then you would not need to add the directory to your path. setuptools Doc or some tutorial