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grist_jupyterlab_widget

This is a JupyterLab extension that connects the Grist and JupyterLab APIs. It's tightly coupled with the JupyterLite deployment in this repo (the parent folder) and doesn't work on its own.

This folder was originally its own repo generated using copier following the extension tutorial. This is the source of a lot of boilerplate configuration that probably isn't all needed but also probably shouldn't be messed with. Usually this extension would be published on PyPI (and maybe NPM) under the package name grist_jupyterlab_widget, but now the parent folder just installs it from the local filesystem.

Code overview

Most of the logic is in src/index.ts.

  1. The entrypoint is the exported plugin: JupyterFrontEndPlugin which JupyterLab picks up as an extension, running activate(app: JupyterFrontEnd) on startup.
  2. The extension adds a <script> tag for grist-plugin-api.js to the page and uses the grist API once it loads.
  3. grist.getOption/setOption and app.serviceManager.contents are used to save/load a notebook file in the widget options. All changes to the notebook are saved immediately.
  4. JupyterLite automatically starts a Pyodide (Python) kernel for the notebook. Once it's ready, we execute the Python code in src/initKernelPy.ts which bootstraps the rest of the Python code - see the parent README for more details.
  5. The Pyodide kernel runs in a separate web worker. To give the user's Python code access to the grist API object in the main browser thread, the Comlink library is used to expose the grist object to the worker. This requires the Worker object which the JupyterLab API doesn't provide, so the Worker constructor is monkeypatched to intercept its creation.

Development install

Below are some of the original instructions included with this repo which may be helpful.

Note: You will need NodeJS to build the extension package.

The jlpm command is JupyterLab's pinned version of yarn that is installed with JupyterLab. You may use yarn or npm in lieu of jlpm below.

# Clone the repo to your local environment
# Change directory to the grist_jupyterlab_widget directory
# Install package in development mode
pip install -e "."
# Link your development version of the extension with JupyterLab
jupyter labextension develop . --overwrite
# Rebuild extension Typescript source after making changes
jlpm build

You can watch the source directory and run JupyterLab at the same time in different terminals to watch for changes in the extension's source and automatically rebuild the extension.

# Watch the source directory in one terminal, automatically rebuilding when needed
jlpm watch
# Run JupyterLab in another terminal
jupyter lab

With the watch command running, every saved change will immediately be built locally and available in your running JupyterLab. Refresh JupyterLab to load the change in your browser (you may need to wait several seconds for the extension to be rebuilt).

By default, the jlpm build command generates the source maps for this extension to make it easier to debug using the browser dev tools. To also generate source maps for the JupyterLab core extensions, you can run the following command:

jupyter lab build --minimize=False

Development uninstall

pip uninstall grist_jupyterlab_widget

In development mode, you will also need to remove the symlink created by jupyter labextension develop command. To find its location, you can run jupyter labextension list to figure out where the labextensions folder is located. Then you can remove the symlink named grist-widget within that folder.