Python issue with importing from submodule including scripts that also import from submodule?

Question

My Python project has the following file structure.

module/
├── __init__.py
├── main.py
│
└── sub_module/
    ├── __init__.py
    ├── foo1.py
    └── foo2.py

My goal is to import a class Bar from foo1.py in main.py:

from sub_module.foo1 import Bar

It's important to know that foo1.py also imports from foo2.py, which currently works fine when I run python3 foo1.py.

from foo2 import some_function

Both init.py files are empty.

Here is the exception that I currently get, when attempting to run python3 main.py:

File "/.../module/main.py", line 3, in <module>
    from sub_module.foo1 import Bar
File "/.../module/sub_module/foo1.py", line 24, in <module>
    from foo2 import some_function

How can I get this working?

Thanks.

Answer 1

The problem is actually with from foo2 import some_function in foo1.py.

When running foo1.py the file is found. This is because the current working directory is sub_module and the path to the file is a relative.

When running main.py this file 'foo2.py' is not found. This is because the current working directory is module. For the relative path to find the file, you would need have from sub_module.foo2 import some_function.

This isn't a great way of importing modules within a package.

The best way is to use absolute locations. This means that whichever file runs the code, it can find the module.

Firstly, removing __init__.py in module. I don't believe this is needed.

# main.py
from sub_module.foo1 import Bar

# foo1.py
from sub_module.foo2 import some_function

If the above is still not working, you need to check your current working directory. This can be done by adding the following to your main.py. It's important that you include every directory from the working directory to the desired file.

import os
print(os.getcwd())

For more information on imports, the documentation is here: https://docs.python.org/3/reference/import.html