fix(json): preserve empty property names during serialization

[Shubham Padkonde (Shubham-Padkonde)]

Overview

Preserve empty-string JSON property names instead of treating them as root values. For example, additional data {"properties": {"": {}}} currently serializes as {"properties": {}}. The writer now distinguishes None (a root value) from "" (a property name), consistently across the JSON writer methods.

Related Issue

Fixes #746

Testing Instructions

From packages/serialization/json, install requirements-dev.txt and run pytest.

• 168 JSON package tests pass on Windows, Python 3.12.
• The new tests cover empty and ordinary property names, root values, nested additional data (including null, false, zero, empty objects and lists), enums and model collections. Against the unchanged source, 22 cases fail and 26 controls pass; all 48 pass with the fix.
• Mypy passes for all 6 package source files; YAPF and isort checks pass.
• Pylint exits successfully with a 10.00/10 score, but reports an existing unrecognized suggestion-mode setting in .pylintrc.

Notes

AI-assisted implementation and validation. The full multi-package/Python-version CI matrix and a generated client against a live API were not run locally. Tests exercise the serializer directly, including the nested payload reported in the issue.

[Vincent Biret (baywet)]

CI is failing due to unit tests failing. Please have a look.

[Copilot]

Copilot review overview

🟡 Changes recommended

Root falsy values are still dropped during serialization.

Get a fresh assessment by requesting another Copilot review.

Review effort: Lite
Findings: 1

Open (1)

• Preserve falsy root values during serialization · New

What changed in this PR

This PR preserves empty-string JSON property names during serialization and adds regression coverage. A critical issue remains: falsy root values can still serialize incorrectly.

Changes:

• Distinguishes None keys from empty-string property names.
• Adds tests for nested data, primitives, enums, and model collections.

File	Summary
packages/​serialization/​json/​tests/​unit/​test_empty_property_names.py	Adds regression tests for empty property names.
packages/​serialization/​json/​kiota_serialization_json/​json_serialization_writer.py	Updates serialization handling for empty property names.

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[Shubham Padkonde (Shubham-Padkonde)]

The multipart CI failures were caused by an internal caller passing an empty string for a JSON root value. With this PR, an empty string correctly means an empty property name, so that caller produced an unwanted wrapper.

Fixed in 79455e0 by passing None from MultipartBody._write_parsable. The three existing multipart regressions fail before this follow-up and pass after it. On Windows/Python 3.13: multipart 13 passed, JSON 168 passed, abstractions 141 passed; abstractions mypy passes all 48 source files, and the changed file passes YAPF/isort checks. The hosted multi-version matrix still needs to rerun.

Prepared and validated with Codex assistance.

[Copilot]

Copilot review overview

🟢 Approval recommended

The only remaining feedback is a non-blocking test-coverage nit.

Review effort: Lite
Findings: None

Resolved since last review (1)

• Preserve falsy root values during serialization

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud