URL Incorrect path Issue

[itsmevichu]

#Issue No. JuyterLab-#12768

Solution:

This issue is because of directly referencing the dictionary object instead of creating a copy in Python. This leads to unintended shared state, where modifications made to the dictionary in one part of the code affect other references to the same dictionary object.

jupyterlab_server/jupyterlab_server/handlers.py

Line 182 in 8b8182d

page_config = super().get_page_config()

This makes a direct access to the page_config dictionary object, meaning that appending the notFoundUrl to this page_config persists throughout the instance. As a consequence, accessing the correct URL after this operation continues to trigger the same error mentioning the same path which is captured while accessing the wrong path.

jupyterlab_server/jupyterlab_server/handlers.py

Line 183 in 8b8182d

page_config["notFoundUrl"] = self.request.path

So, creating a shallow copy of the object fixes this issue.👇

jupyterlab_server/jupyterlab_server/handlers.py

Line 182 in 3be24ab

page_config = super().get_page_config().copy()

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[JasonWeill]

@itsmevichu Thanks for opening this PR! This fix doesn't address the underlying issue, where both the LabHandler and the NotFoundHandler get invoked upon visiting a URL like /lab/workspaces-bad/…. In the case of a bad URL, one that doesn't correspond to a lab session or a file, we should only invoke NotFoundHandler once. Note that NotFoundHandler extends and calls LabHandler.

[itsmevichu]

@JasonWeill Thanks for your quick response, I am seeing that both NotFoundHandler and LabHandler is invoked while accessing the bad URL, but the persisted state of the path_config is what causing the I suppose.
Please have a look into this

[JasonWeill]

I tested this with the following URLs locally, as documented here: https://jupyterlab.readthedocs.io/en/stable/user/urls.html

• /
• /lab
• /lab/tree/hello.ipynb
• /lab/tree/myoutput/foo.ipynb
• /lab/tree/demo.ipynb#Mysection
• /lab/tree/demo.ipynb?#Mysection
• /lab/workspaces/foo/tree/hello.ipynb?reset

All loaded as expected.

Incorrect paths, like by misspelling workspaces, produced errors that only persisted for one page view.

Great work @itsmevichu !

[itsmevichu]

Thank you so much @JasonWeill 😉

[welcome]

Congrats on your first merged pull request in this project! 🎉

Thank you for contributing, we are very proud of you! ❤️

[JasonWeill]

This is now available in JupyterLab Server version 2.25.3: https://github.com/jupyterlab/jupyterlab_server/releases/tag/v2.25.3

Thanks again @itsmevichu for your contribution!