update get_path() to return a path relative to root_dir

[dlqqq]

get_path() now returns a path relative to its configured root_dir trait, which should be set to the server root. Developers using jupyter_server_fileid (e.g. scheduling, RTC) have found that relative paths are being used far more in the Jupyter ecosystem than absolute ones, and thus get_path() should default to returning a relative path instead.

To revert back to the old behavior, this can be done manually via:

path = file_id_manager.get_path(id)
os.path.join(file_id_manager.root_dir, path) 

If there is a demonstrated use-case for absolute paths, I'd be happy to add an argument absolute: bool to get_path() that allows for users to be returned an absolute path. However, at the present moment, there are no known usecases for it.

[dlqqq]

cc @davidbrochart

[codecov-commenter]

Codecov Report

Base: 78.49% // Head: 78.18% // Decreases project coverage by -0.30% ⚠️

Coverage data is based on head (562c72f) compared to base (ef5ff9d).
Patch coverage: 70.27% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #21      +/-   ##
==========================================
- Coverage   78.49%   78.18%   -0.31%     
==========================================
  Files           5        5              
  Lines         372      408      +36     
  Branches       52       62      +10     
==========================================
+ Hits          292      319      +27     
- Misses         65       66       +1     
- Partials       15       23       +8     

Impacted Files	Coverage Δ
jupyter_server_fileid/manager.py	88.47% <33.33%> (+0.14%)	⬆️
jupyter_server_fileid/pytest_plugin.py	87.65% <73.52%> (-10.27%)	⬇️

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[davidbrochart]

Don't you need to expand the user (to convert ~ into e.g. /home/david)?

[dlqqq]

Good question! The paths stored in the Files table are completely normalized and absolute, meaning they should never contain ~/, ./, or ../. If you are noticing that the returned paths contain any of those substrings, please file a bug report.

[kevin-bates]

I think @davidbrochart is referring to the value in self.root_dir...

>>> import os
>>> os.path.relpath("/Users/kbates/notebooks/experiments", "~/notebooks")
'../../../../../../../../../notebooks/experiments'
>>> os.path.relpath("/Users/kbates/notebooks", os.path.expanduser("~/notebooks"))
'.'

However, the currently configurable root_dir is validated to ensure its value is absolute. I use currently because this attribute should probably derive from the associated ContentsManager per #24 and not be user-configurable. In that case, the FileID service will likely want to perform the expansion.