nil68657 opened a new pull request, #53263: URL: https://github.com/apache/arrow/pull/53263
### Rationale for this change The dataset JSON reader derived the physical schema from the complete lines of the first block only. A file holding one object without a newline produced an empty schema, so every column was read as null. Parse the whole block when it already covers the entire file. ### What changes are included in this PR? - `cpp/src/arrow/dataset/file_json.cc` ### Are these changes tested? Yes. A regression test in `cpp/src/arrow/dataset/file_json_test.cc` fails without the change and passes with it; the surrounding test module/binary passes. ### Are there any user-facing changes? See the rationale above. ### Was AI used for this PR? This PR is a joint contribution from Nilanjan Chatterjee ([@nil68657](https://github.com/nil68657)) and Claude (Claude Opus 5.5, via Claude Code). Nilanjan chose the issue and directed the work; Claude reproduced the bug, wrote the fix, the test and this description. **PR code and description written by:** - [ ] Human - [x] AI **Reviewed before submission by:** - [ ] Human - [x] AI - [ ] Not reviewed * GitHub Issue: #45394 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
