NOMAD's schema example plugin

Getting started

Fork the project

Go to the github project page https://github.com/nomad-coe/nomad-schema-plugin-example, hit fork (and leave a star, thanks!). Maybe you want to rename the project while forking!

Clone your fork

Follow the github instructions. The URL and directory depends on your user name or organization and the project name you choose. But, it should look somewhat like this:

git clone git@github.com:markus1978/my-nomad-schema.git
cd my-nomad-schema

Install the dependencies

You should create a virtual environment. You will need the nomad-lab package (and pytest). You need at least Python 3.9.

python3 -m venv .pyenv
source .pyenv/bin/activate
pip install --upgrade pip
pip install '.[dev]' --index-url https://gitlab.mpcdf.mpg.de/api/v4/projects/2187/packages/pypi/simple

Note! Until we have an official pypi NOMAD release with the plugins functionality. Make sure to include NOMAD's internal package registry (e.g. via --index-url).

Run the tests

Make sure the current directory is in your path:

export PYTHONPATH=.

You can run automated tests with pytest:

pytest -svx tests

Run linting

ruff check .

Run auto-formatting

This is entirely optional. To add this as a check in github actions pipeline, uncomment the ruff-formatting step in ./github/workflows/actions.yaml.

ruff format .

You can parse an example archive that uses the schema with nomad (installed via nomad-lab Python package):

nomad parse tests/data/test.archive.yaml --show-archive

Developing your schema

You can now start to develop you schema. Here are a few things that you might want to change:

• The metadata in nomad_plugin.yaml.
• The name of the Python package nomadschemaexample. If you want to define multiple plugins, you can nest packages.
• The name of the example section ExampleSection. You will also want to define more than one section.
• When you change module and class names, make sure to update the nomad_plugin.yaml accordingly.

Build the python package

The pyproject.toml file contains everything that is necessary to turn the project into a pip installable python package. Run the python build tool to create a package distribution:

pip install build
python -m build --sdist

You can install the package with pip:

pip install dist/nomad-schema-plugin-example-1.0.tar.gz

Read more about python packages, pyproject.toml, and how to upload packages to PyPI on the PyPI documentation.

Next steps

To learn more about plugins, how to add them to an Oasis, how to publish them, read our documentation on plugins: https://nomad-lab.eu/docs/plugins/plugins.html.