Unable to find submodule when poetry install or poetry build

[juanjomendezhealios]

Hello 👋 , I'm trying to create a package that contains multiple subpackages. My intention is to create a package with extras so we can use it to only install the required subpackages in another environment, using pip install my_package.whl[sub_package_a].

The structure of my project is as follow:

directory
├── configs
├── dist
├── docs
├── package
│   ├── __init__.py
│   ├── sub_package_a
│       └── __init__.py
│       └── script_a.py
│       └── pyproject.toml
│   ├── sub_package_b
│       └── __init__.py
│       └── script_b.py
│       └── pyproject.toml
├── pyproject.toml

The structure of directory/pyproject.toml is:

[tool.poetry]
name = "package"
version = "0.1.0"
authors = ["Juanjo Méndez <juanjo.mendez@>"]
readme = "README.md"
packages = [{ include = "package" }]

[tool.poetry.dependencies]
python = ">=3.9,<3.10"
sub_package_a = { path = "./package/sub_package_a", develop = true, optional = true }

[tool.poetry.extras]
sub_package_a = ["sub_package_a"]

[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api"

On the other hand, the structure of directory/package/package_a/pyproject.toml is:

[tool.poetry]
name = "sub_package_a"
version = "0.1.0"
authors = ["Juanjo Méndez <juanjo.mendez@>"]
readme = "README.md"
packages = [{ include = "./**/*.py" }]
include = [{ path = "./**/*.json", format = ["sdist", "wheel"] }] # To include files that are not python scripts

[tool.poetry.dependencies]
python = ">=3.9,<3.10"
python-dotenv = "^1.0.1"

[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api"

When I do poetry install -E sub_package_a, the environment is created and when I list the packages installed in there, I can observe the package sub_package_a. Although, when I start a python shell, I try to import the sub-package (import sub_package_a) and it raises an error of ModuleNotFound.

Furthermore, I when I ran poetry build, the whl and sdist files are created correctly, and the sub_package_a can be installed via pip install my_package.whl[sub_package_a]. Although, it happens the same as before, the package is installed (that is what pip shows), but when I try to import the module, it is not found.

Can someone help me with this? 🙏

I have observed that poetry is very powerful, but there are some things that are not covered in the documentation and are pretty interesting to know; e.g. creating a package with extras to not to install the full package in another environment, only the necessary stuff.