Error Installing @jupyter-widgets/[email protected]

[jhamet93]

Description

ValueError: "@jupyter-widgets/[email protected]" is not a valid extension:
schemaDir is empty: "./schema"

Reproduce

jupyter labextension install @jupyter-widgets/[email protected] within the latest JupyterLab3 environment

Expected behavior

Lab extension successfully installs

Context

Attempting to upgrade company JupyterLab offering to 3.X so bumping this installation

[jtpio]

Thanks @jhamet93 for reporting this issue 👍

I could reproduce it locally in a new environment with:

mamba create -n tmp python=3.9 jupyterlab=3 -y
conda activate tmp
jupyter labextension install @jupyter-widgets/[email protected]

The schema seems to be correctly bundled in the source extension. So maybe it's an issue with the jupyter labextension install command and the handling of schemas.

Attempting to upgrade company JupyterLab offering to 3.X so bumping this installation

Normally this command is not stricly necessary with JupyterLab 3.0. Installing ipywidgets>=7.5 in the same environment as JupyterLab should also install the @jupyter-widgets/jupyterlab-manager extension automatically, using the prebuilt extension system added in JupyterLab 3.0.

Would you be able to check whether this fixes the issue?

[jhamet93]

I was able to fix the issue using as you stated but in a slightly hacky manner. At Twitter, we use pexes to conceal our Python environment which means exposing the contents of this pex a bit hacky in order for the prebuilt extension system to discover the correct location.

Is still being able to install this extension via jupyter labextension install for 3.X an expected behavior ? If so, I'm happy to follow along an issue or introduce a possible pull request to resolve this.

[jtpio]

Is still being able to install this extension via jupyter labextension install for 3.X an expected behavior ?

Yes this is still supported.

It looks it is hitting that line in the extension manager code in JupyterLab: https://github.com/jupyterlab/jupyterlab/blob/2b8a2cedcdb7cd4d3aac556692b146e8712a0e8f/jupyterlab/commands.py#L2078

I wonder if this is because the schemaDir in jupyterlab_widgets starts with ./ here:

ipywidgets/python/jupyterlab_widgets/package.json

Line 95 in 6dff84d

"schemaDir": "./schema"

Which would make the string comparison fail. For reference the cookiecutter does not seem to be using the leading ./: https://github.com/jupyterlab/extension-cookiecutter-ts/blob/1657093417dd510665defd87006ef5a91ea4be5e/%7B%7Bcookiecutter.python_name%7D%7D/package.json#L89

[jtpio]

FYI @jhamet93 jupyterlab/jupyterlab#11427 should provide a fix for this, in case you would like to check it out.