Add support for opening a document with a different factory

[jtpio]

First steps towards jupyterlab/retrolab#290.

For example when opening a JSON file with different factories:

open-factory-edit.mp4

This is also useful so folks can open notebooks with the text editor too:

open-factory-notebook.mp4

TODO

• Basic support for custom factories when opening a document
• Should this work for arbitrary widgets, like the settings editor? Decide whether to do this in this PR or as follow-up -> deferring to another PR / issue, see this comment for a proof of concept: Add support for opening a document with a different factory #6315 (comment)
• Should the ?factory= URL parameter be removed from the URL after the document is opened? -> keeping it when it is not default, so the page can be reloaded and the document renders the same

[github-actions]

👈 Launch a Binder on branch jtpio/notebook/factories

[jtpio]

Should the ?factory= URL parameter be removed from the URL after the document is opened?

Keeping it could be useful, so it can be copy pasted and sent to other people (or bookmarked). But some folks used to the classic notebook might wonder what this actually means.

[jtpio]

Should this work for arbitrary widgets, like the settings editor?

Probably this one could have special treatment.

Right now the NotebookShell only allows one widget to be added to the main area:

notebook/packages/application/src/shell.ts

Lines 140 to 143 in c133317

	if (this._main.widgets.length > 0) {
	// do not add the widget if there is already one
	return;
	}

An alternative could be to add it to the tree / dashboard page:

[jtpio]

An alternative could be to add it to the tree / dashboard page:

Some proof of concept to explore this:

tree-setting-editor.mp4

Posting here for visibility, but should probably be explored more in another PR.

[fcollonval]

Thanks a lot for starting @jtpio.

I got a call yesterday with @parmentelat about using Jupytext in notebook v7 (something we cannot overlook). Starting from v1.13.2, Jupytext uses the document factory to display files with the notebook editor. So we definitely should check this PR works with Jupytext.

cc @mwouts

[jtpio]

Thanks @fcollonval for the heads up. I think it should work with the Jupytext Notebook factory. Maybe we'll need to make sure it properly opens with the /notebook URL.

I installed jupytext with pip install jupytext locally and the server and lab extensions seem to be properly installed.

$ jupyter server extension list
Config dir: PREFIX/etc/jupyter
    jupyterlab enabled
    - Validating jupyterlab...
      jupyterlab 4.0.0a22 OK
    jupytext enabled
    - Validating jupytext...
      jupytext 1.13.7 OK
    notebook_shim enabled
    - Validating notebook_shim...
      notebook_shim  OK

$ jupyter labextension list
JupyterLab v4.0.0a22
PREFIX/share/jupyter/labextensions
        jupyterlab-jupytext v1.3.8 enabled  X (python, jupytext)
        @jupyter-notebook/lab-extension v7.0.0-alpha.1 enabled OK

The lab extension loads fine. However the jupytext server extension seems to be failing on startup: with

[W 2022-03-19 17:15:02.569 ServerApp] jupytext | extension failed loading with message: name 'build_jupytext_contents_manager_class' is not defined

[jtpio]

Ah looks like it tries to import LargeFileManager from notebook.services.contents.largefilemanager here:

https://github.com/mwouts/jupytext/blob/d25c0c640ca0b2c1fb0e15b99be81bb82d2fe5ab/jupytext/contentsmanager.py#L573-L581

Which could be related since these are not available in Notebook v7... (but could be shimmed?)

Does jupytext work with Jupyter Server / JupyterLab only? Or does it expect the classic notebook server (via the notebook package) to be available too?

[jtpio]

Ah looks like it tries to import LargeFileManager from notebook.services.contents.largefilemanager here:

This looks good when running with the fix proposed in mwouts/jupytext#933:

jupytext-factory.mp4

Just need to open it under /notebooks to match the behavior of the classic notebook v6.

[fcollonval]

Thanks a lot for testing it with Jupytext.

Just need to open it under /notebooks to match the behavior of the classic notebook v6.

How do you plan to support that case? I think we will be able to supported it out of the box by applying jupyterlab/jupyterlab#11540 in Jupytext.

[jtpio]

I think we will be able to supported it out of the box by applying jupyterlab/jupyterlab#11540 in Jupytext.

Maybe only the Notebook factory should open in /notebooks then? Looks like this would indeed work out of the box with this PR?

[jtpio]

Documents now open with their default factory, for example when double-clicking on the item in the file browser.

When opened with a different factory, ?factory= is kept in the URL so the browser tab can be reloaded and the document renders the same:

default-factory.mp4

This also means that some files like JSON now open with the JSON viewer instead of the text editor by default. This differs from the behavior of the classic notebook and could maybe be customized via the settings if needed. Opening with the default JSON viewer by default is however useful because it's coherent with the behavior in JupyterLab.

[jtpio]

cc @fcollonval if you would like to have a look.

Happy to get this in and iterate further. We can also make a new alpha release if that can ease development of third-party extensions like jupytext.

[fcollonval]

Thanks a lot for this one.

[parmentelat]

indeed @jtpio many thanks !

[jtpio]

Thanks @fcollonval and @parmentelat!

Let's get this in then, and I'll start a new release right after.

[fcollonval]

Maybe only the Notebook factory should open in /notebooks then?

Looking into this briefly, the trouble for jupytext are actually for file types already defined in core (like .py or .md). I was thinking to use the Router to deal with path like /notebooks/not/a-ipynb-file.ext URL to redirect to the /edit/not/a-ipynb-file.ext?factory=Jupytext%20Notebook if the extension is supported by Jupytext. What do you think @jtpio ?

[jtpio]

Thanks @fcollonval let's track this in #6324.