File Load Error - content.indexOf is not a function when opening a text file in JupyterLab

[mwouts]

If I try to open a text notebook, say World population.md on , then I get this error:

The version of JupyterLab used on Binder is 2.2.0.

[mwouts]

Locally with JupyterLab 2.2.6 I don't reproduce the issue

[dfm]

I'm finding the same with JupyterLab 2.2.9 and jupytext 1.7.0. Any ideas about what's happening?

[dfm]

FWIW: Downgrading to jupytext 1.6.0 fixed the issue for me.

[mwouts]

Thank you @dfm for the input, that's very helpful. The major change between 1.6.0 and 1.7.0 is a refactoring of Jupytext's contents manager, I will have a look at it and see if I can identify any difference in how text notebooks are loaded between the two...

[mwouts]

Indeed, there is a slight difference in the model returned by the new contents manager, and that may be the cause of the issue.

With Jupytext 1.7.0 the model for a text notebook is

{'name': 'text.py', 'path': 'text.py', 'last_modified': datetime.datetime(2020, 11, 15, 21, 58, 7, 683993, tzinfo=<notebook._tz.tzUTC object at 0x7f8a59918640>), 'created': datetime.datetime(2020, 11, 15, 21, 58, 7, 683993, tzinfo=<notebook._tz.tzUTC object at 0x7f8a59918640>), 'content': {'nbformat': 4, 'nbformat_minor': 4, 'metadata': {'jupytext': {'notebook_metadata_filter': '-all', 'cell_metadata_filter': '-all', 'text_representation': {'extension': '.py', 'format_name': 'percent'}}, 'kernelspec': {'name': 'jupytext-dev', 'language': 'python', 'display_name': 'jupytext-dev'}}, 'cells': [{'cell_type': 'code', 'metadata': {}, 'execution_count': None, 'source': '1 + 1', 'outputs': []}]}, 'format': 'text', 'mimetype': 'text/x-python', 'size': 11, 'writable': True, 'type': 'notebook'}

while in Jupytext 1.6.0 that was

{'name': 'text.py', 'path': 'text.py', 'last_modified': datetime.datetime(2020, 11, 15, 22, 3, 9, 136043, tzinfo=<notebook._tz.tzUTC object at 0x7fc9e013c910>), 'created': datetime.datetime(2020, 11, 15, 22, 3, 9, 136043, tzinfo=<notebook._tz.tzUTC object at 0x7fc9e013c910>), 'content': {'nbformat': 4, 'nbformat_minor': 4, 'metadata': {'jupytext': {'notebook_metadata_filter': '-all', 'cell_metadata_filter': '-all', 'text_representation': {'extension': '.py', 'format_name': 'percent'}}, 'kernelspec': {'name': 'jupytext-dev', 'language': 'python', 'display_name': 'jupytext-dev'}}, 'cells': [{'cell_type': 'code', 'metadata': {'trusted': True}, 'execution_count': None, 'source': '1 + 1', 'outputs': []}]}, 'format': 'json', 'mimetype': None, 'size': 11, 'writable': True, 'type': 'notebook'}

the difference is

• 'format': 'json', 'mimetype': None in v1.6.0 vs
• 'format': 'text', 'mimetype': 'text/x-python' in v1.7.0

That should be fairly easy to fix...

[mwouts]

@dfm, may I ask you to give a try to the proposed fix? I mean:

pip install git+https://github.com/mwouts/jupytext.git

Thanks!

[mwouts]

The issue is gone on Binder. I will make a few more tests and distribute the new version later today if everything works fine.

[dfm]

@mwouts: I can confirm that this fix works for me. Thanks!

[mwouts]

Excellent! Thank you for the confirmation.