Python imports in nested structure

Question

There is the following structure:

project/
   I-----main.py
   I-----src/
          I----__init__.py (empty)
          I----util.py
          I----shared/
                  I----__init__.py (empty)
                  I----hello.py 


#main.py
from src import util

#util.py (runs without errors)
from shared import hello

#hello.py (runs without errors)
def hello():
    print("Hello")

I try to run main.py, get result

ModuleNotFoundError: No module named 'shared'

How to repair imports in main.py?

Why are there two ``__init__.py``s? Please check https://stackoverflow.com/questions/2164258/is-it-not-possible-to-define-multiple-constructors-in-python — new Q Open Wid, May 21 '21 at 11:53
@newQOpenGLWidget one `__init__.py` per package, that looks correct to me. `__init__.py` is **not** a constructor. — SuperStormer, May 21 '21 at 11:55

score 1 · Answer 1 · answered May 21 '21 at 11:53

1

You probably want to from src.shared import hello

answered May 21 '21 at 11:53

DSteman

1,388
2
12
25

This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - [From Review](/review/low-quality-posts/29025223) – mufazmi May 21 '21 at 18:25
@mufazmi: This one does provide an answer. That said, [subsequently contributed answers](https://stackoverflow.com/a/67636545/3025856) reiterate this suggestion but with a lot more detail. – Jeremy Caney May 21 '21 at 18:55
it isnt a stable and always working solution – kostya May 28 '21 at 10:27

score 1 · Answer 2 · edited May 21 '21 at 18:59

There are two main reasons for such kind of failures:

Module import: You are not importing the module correctly. You can either import it using the __init__.py of a module by mentioning the import of its sub-module or you can directly put the full path via an import. For instance, you can use from src.shared import hello. Or, in your __init__.py file, inside the src module, you could add from shared import hello. This will also work because whenever you import a module, the first thing that is being run in that module is the __init__.py of that file.
Circular imports: This is not your case, but I am bringing this up because many times we ignore this and get trapped. A circular import occurs when two modules depend on each other. I have described why it happens and how to avoid it in the post, What is Circular Import and how to avoid it.

score 0 · Accepted Answer · answered May 24 '21 at 07:55

i found possible solution (works well):


    #util.py
    import sys
    from pathlib import Path
    
    root = Path(__file__).parent.parent #depends on file's place in general structure
    sys.path.append(str(root))
    import src.shared.hello as hello

score -1 · Answer 4 · answered May 21 '21 at 12:02

You need to use a relative import:

from .shared import hello

If you run util.py normally, .../project/src is appended to sys.path and Python can find the import. However, when you run main.py, .../project/ is appended to sys.path, and Python can't find the shared module. By using a relative import, Python looks up the module name relative to the current package, and can find the shared module.

See also: Relative imports for the billionth time

Python imports in nested structure

4 Answers4