Fix get_json_object dropping object fields that follow an empty key

[vuule]

Description

get_json_object used a zero-length name as the signal that no name was present, so the legal JSON key "" was indistinguishable from an absent name and the following colon was left unconsumed, leading to failed parsing of the whole row. For example, $.a on {"":0,"a":1} returned null instead of 1, while {"a":1,"":0} worked.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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[vuule]

/ok to test a2330ee

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📥 Commits

Reviewing files that changed from the base of the PR and between 25b1b5a and a2330ee.

📒 Files selected for processing (2)

• cpp/src/json/json_path.cu
• cpp/tests/json/json_tests.cpp

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📝 Summary

Summary by CodeRabbit

• Bug Fixes
  • Improved JSON parsing for object names, including empty-string keys.
  • Ensured malformed or incomplete object names are correctly rejected.
  • Preserved JSONPath field selection for objects containing empty-string keys across supported input formats and value types.

Walkthrough

JSONPath name parsing now distinguishes absent names from empty-string keys, propagates parsing failures, and requires a colon after parsed names. Tests cover field selection from objects containing empty-string keys in multiple layouts and value types.

Changes

JSONPath empty-key handling

Layer / File(s)	Summary
Name parsing validation cpp/src/json/json_path.cu	The parser documents empty-string keys and requires whitespace followed by : after every successfully parsed name. It also propagates non-success results from parse_string.
Empty-key regression coverage cpp/tests/json/json_tests.cpp	ObjectWithEmptyKey verifies selection of the "a" field from objects containing empty-string keys across scalar, object, array, and formatting variants. The SPDX notice includes affiliates.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to a2330

JSONPath parsing now correctly handles empty-string object keys, allowing subsequent fields to be retrieved as expected. The implementation and regression coverage address the stated behavior change with no concrete unresolved current-head risk.

Suggested reviewers: davidwendt

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description directly explains the empty-key parsing defect, its effect on get_json_object, and the test coverage for the fix.
Title check	✅ Passed	The title clearly identifies the main change: preventing get_json_object from dropping fields that follow an empty object key.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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