lsp issues with opencv-python

I use the neovim plugin nvim-lspconfig and for python, it requires minimal setup and works fine most of the time. One issue that I repeatedly face when working on python projects involving image manipulation is the lack of code-completion and missing type stub errors for the cv2 (opencv-python) package. The working solution is to manually generate type stubs for the package.

steps

1. Install the mypy package, it has the stubgen command that will generate the type stubs.
2. Find cv2 package directory and store in an environment variable (for now)

   export CV2_DIR=$(python -c 'import cv2, os; print(os.path.dirname(cv2.__file__))')
   

3. Generate stub files in the package directory

   stubgen -m cv2 -o $CV2_DIR
   

4. The previous command generates the stub file and names it <package_name>.pyi (cv2.pyi in this case) but it has to be renamed to __init__.pyi in order to be read by the LSP.

   mv $CV2_DIR/cv2.pyi $CV2_DIR/__init__.pyi
   

5. [Optional] unset the CV2_DIR environment variable.

   unset CV2_DIR
   

Code completion should work now.