When determining mag realpaths, treat schemeless uris as local

[fm3]

Path.of fails for URIs without scheme. We want to assume local files in this case.

I don’t like that this is encoded with null and we need to check this in so many places. Refactoring issue for that: #8762

Steps to test:

• In a datasource-properties.json, add a mag with a path that is absolute and inside of the organization dir.
• Dataset scanning should not report Failed to determine real paths of mags of <ds>. Realpaths should be set correctly in the DB.

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• Considered common edge cases
• Needs datastore update after deployment

[coderabbitai]

📝 Walkthrough

Walkthrough

This change updates URI and path handling in the DataSourceService class. It adjusts the construction of Path objects to use only the path component of a URI and adds an explicit null check before evaluating if a URI scheme is remote, preventing possible null pointer exceptions.

Changes

Cohort / File(s)	Change Summary
DataSourceService URI & Path Handling webknossos-datastore/app/com/scalableminds/webknossos/datastore/services/DataSourceService.scala	Refactored getMagPathInfo to use only the URI's path component for Path construction; updated getMagURI to check for null before remote scheme evaluation, improving null safety.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Possibly related PRs

• Interpret paths without scheme to be file in DataVaultService #8761: Also addresses URI scheme nullability and path interpretation in the datastore, focusing on safe URI handling.
• Stricter checks for explicit local mag paths #8547: Modifies mag path and URI validation in DataSourceService.scala, related to path and URI handling but in different methods.
• Resolve symbolic links to mags and store them in db #8350: Enhances symbolic link resolution and real path reporting for mags and layers, affecting similar code areas for path and URI handling.

Suggested reviewers

• frcroth

Poem

A bunny hopped through code so neat,
Fixing URIs with nimble feet.
Paths now clear, no nulls to fear,
The datastore runs without a tear.
With careful checks and thoughtful care,
Bugs are gone from this warren’s lair! 🐇✨

Note

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Learn more here, or try it out under "Finishing Touches" below.

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📜 Recent review details

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Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between b283045 and b5d6736.

📒 Files selected for processing (1)

• webknossos-datastore/app/com/scalableminds/webknossos/datastore/services/DataSourceService.scala (2 hunks)

🧰 Additional context used

🧠 Learnings (1)

webknossos-datastore/app/com/scalableminds/webknossos/datastore/services/DataSourceService.scala (1)

Learnt from: frcroth
PR: #8609
File: app/models/dataset/Dataset.scala:753-775
Timestamp: 2025-05-12T13:07:29.637Z
Learning: In the updateMags method of DatasetMagsDAO (Scala), the code handles different dataset types distinctly:

1. Non-WKW datasets have magsOpt populated and use the first branch which includes axisOrder, channelIndex, and credentialId.
2. WKW datasets will have wkwResolutionsOpt populated and use the second branch which includes cubeLength.
3. The final branch is a fallback for legacy data.
   This ensures appropriate fields are populated for each dataset type.

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (2)

• GitHub Check: backend-tests
• GitHub Check: build-smoketest-push

🔇 Additional comments (2)

webknossos-datastore/app/com/scalableminds/webknossos/datastore/services/DataSourceService.scala (2)

141-141: LGTM! Correctly extracts path component from URI.

This change properly addresses the issue where Path.of() fails for schemeless URIs by extracting only the path component using getPath(). Since we're already in the non-remote branch, this ensures that both schemeless URIs and regular file paths are handled correctly.

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162-162: LGTM! Essential null check prevents NullPointerException.

The null check for uri.getScheme is crucial as it prevents potential NullPointerException when handling schemeless URIs. This ensures that URIs without schemes are correctly treated as non-remote (local), which aligns with the PR's objective.

✨ Finishing Touches

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch realpath-without-uri-scheme

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[frcroth]

Alternatively use the Option.apply method around uri.getScheme and work with options in isRemoteScheme?

[fm3]

I think this null check is ok for the moment. In #8762 I hope we can get rid of the null entirely