ModuleNotFoundError: No module named after publishing a package to PyPI with Poetry - python-import

Question

I created a package with poetry with this folder instruction:
my-app/
├─ src/
│ ├─ __init__.py
│ ├─ models/
│ ├─ helpers/
│ ├─ file_a.py
│ ├─ file_b.py
├─ __init__.py
├─ tests/
│ ├─ tests.py
├─ __init__.py
├─ pyproject.tmol
In file_a.py I do from file_b import FileB and then I can it use like: b = FileB(),
and in my tests.py, I do from file_a import FileA and all works fine while doing development, but when I publish the package to PyPi and try to use in another project:
from file_a import FileA
a = FileA()
I get something like:
Traceback (most recent call last):
File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8/runpy.py", line 194, in _run_module_as_main
return _run_code(code, main_globals, None,
File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8/runpy.py", line 87, in _run_code
exec(code, run_globals)
File "src/__main__.py", line 1, in <module>
from kinetic_sdk import KineticSdk
File "/Users/me/Library/Caches/pypoetry/virtualenvs/kinetic-python-example-17HFj6yJ-py3.8/lib/python3.8/site-packages/file_a.py", line 1, in <module>
from file_b import FileB
ModuleNotFoundError: No module named 'file_b'
FWIW: package name would be file-a

Answer 1

I just published my first package to PyPI and ran into the same issue. This is how I solved it.
You can install your package like it is indicated on the MyPI website (in my case: pip install nbdbsession).
Your import, however, will be based on the folder name.
We need to change your file structure.
This is your original structure:
my-app/
├─ src/
│ ├─ __init__.py
│ ├─ models/
│ ├─ helpers/
│ ├─ file_a.py
│ ├─ file_b.py
├─ __init__.py
├─ tests/
│ ├─ tests.py
├─ __init__.py
├─ pyproject.tmol
This is what you need to change:
The + indicates something you need to add
The - indicates a removal
The ~ indicates a change
my-app/
├─ src/
+ ---myapp/ # put everything into the folder "src/myapp/"
│ ├─ __init__.py
│ ├─ models/
│ ├─ helpers/
│ ├─ file_a.py
│ ├─ file_b.py
- ├─ __init__.py # you only need the __init__.py file in "src/myapp"
├─ tests/
│ ├─ tests.py
- ├─ __init__.py # same here: no need to store that file here
~ ├─ pyproject.toml # there was a typo here :)
Or in essence:
my-app/
├─ src/
| |-myapp/
│ ├─ __init__.py
│ ├─ models/
│ ├─ helpers/
│ ├─ file_a.py
│ ├─ file_b.py
Once your package is published, you can run import myapp, where myapp is the name of the folder.
Another Example
Let's say you had this struct:
my-app/
├─ src/
|-zen/
├─ __init__.py
├─ ...
You would indeed import zen after pip install my-app.
A few more notes:
Why do you need the __init__.py file? This file will let Python know that the current directory is a module / package. Therefore, you only need it in your package folders, not in the root directory or in src.
When you import within a module, you usually do relative imports (python docs).
So instead of from file_b import FileB you would use from .file_b import FileB.
And if you want to import file_b after installing your package with pip install myapp, you need to from myapp import file_b.
I hope that helps!