Fix TypeScript derived model serialization dispatch by Shubham-Padkonde · Pull Request #8241 · microsoft/kiota

Shubham Padkonde (Shubham-Padkonde) · 2026-09-21T10:41:56Z

A base serializer dispatches to a derived serializer with isSerializingDerivedType = true, but the derived serializer immediately returns when that flag is set. This drops the derived properties. Removing that guard alone can also cause duplicate property writes when invoking a derived serializer directly.

Dispatch to a mapped serializer before writing properties and return its result. When serializing inherited properties, pass the flag to suppress further discriminator dispatch while still writing the parent fields. Ignore mappings back to the current type so a base-type discriminator value cannot recurse into itself.

Update the writer regressions for the null guard, parent call and discriminator dispatch; the discriminator test also covers a self-mapping and verifies dispatch precedes property writes. Existing literal-escaping checks remain passing.

Developed with Codex assistance.

Validation:

Three updated writer regressions fail against the original implementation. All 189 TypeScript writer/refiner tests pass after the change.
The attached schema from Typescript client generation doesn't handle allOf correctly when serializing, again in 1.28.0 #6777 reproduces dropped derived fields in a generated-client runtime check before the fix.
Afterward, the generated client compiles with TypeScript 5.8.2 and Kiota packages 1.0.0-preview.107. An extension of the attachment covers ten runtime cases: base/direct derived calls, three-level inheritance, self-mapping, unknown/missing discriminators, plus null controls. A recording writer verifies exact-once field writes; the real JSON writer verifies the serialized values and absence of duplicate keys. No HTTP requests were sent.
.NET 10 generator build and scoped C# formatting verification pass. The generator build emits worktree SourceLink warnings.

Vincent Biret (baywet) · 2026-09-21T13:06:37Z

Shubham Padkonde (@Shubham-Padkonde) your behaviour is disruptive, opening about 30 PRs on the repos in a couple of hours time, most likely code that was AI generated and not tested/reviewed, will only clog our review pipeline. Please stop opening additional pull requests and work on the comments added to existing ones. We have turned on pull requests limits on this repository, and will proceed to blocking you at the organization level if additional pull requests are opened on other repositories before the already opened ones are reviewed and closed/or merged.

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🟢 Approval recommended

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What changed in this PR

Fixes TypeScript derived-model serialization by preserving inherited and derived properties without duplicate writes or recursive dispatch.

Changes:

Dispatches mapped serializers before local property writes.
Prevents self-mapping recursion.
Updates regression tests and changelog documentation.

File	Summary
`tests/Kiota.Builder.Tests/Writers/TypeScript/CodeFunctionWriterTests.cs`	Expands serializer regression coverage.
`src/Kiota.Builder/Writers/TypeScript/CodeFunctionWriter.cs`	Corrects discriminator and inheritance serialization flow.
`CHANGELOG.md`	Documents the TypeScript serialization fix.

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Vincent Biret (baywet) · 2026-09-23T11:20:41Z

Shubham Padkonde (@Shubham-Padkonde) this PR is conflicting, would you mind handling the conflicts when you have a minute please?

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github-actions · 2026-09-23T17:01:29Z

This pull request has conflicting changes, the author must resolve the conflicts before this pull request can be merged.

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github-actions · 2026-09-23T17:17:09Z

Conflicts have been resolved. A maintainer will take a look shortly.

github-actions · 2026-09-23T18:23:08Z

This pull request has conflicting changes, the author must resolve the conflicts before this pull request can be merged.

github-actions · 2026-09-24T01:03:14Z

Conflicts have been resolved. A maintainer will take a look shortly.

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github-actions · 2026-09-25T00:18:11Z

This pull request has conflicting changes, the author must resolve the conflicts before this pull request can be merged.

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github-actions · 2026-09-25T01:34:15Z

Conflicts have been resolved. A maintainer will take a look shortly.

github-actions · 2026-09-25T21:24:13Z

This pull request has conflicting changes, the author must resolve the conflicts before this pull request can be merged.

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github-actions · 2026-09-25T21:45:13Z

Conflicts have been resolved. A maintainer will take a look shortly.

Fix TypeScript derived model serialization dispatch

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Shubham Padkonde (Shubham-Padkonde) requested a review from a team as a code owner September 21, 2026 10:42

Vincent Biret (baywet) requested a lite review from Copilot September 21, 2026 13:02

Copilot started reviewing on behalf of Vincent Biret (baywet) September 21, 2026 13:03 View session

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Merge main to resolve PR 8241 changelog conflict

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Merge main to resolve PR 8241 changelog conflict

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Merge main to resolve PR 8241 changelog conflict

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Merge main to resolve PR 8241 changelog conflict

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Merge main to resolve PR 8241 changelog conflict

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Merge main to resolve PR 8241 changelog conflict

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Merge main to resolve PR 8241 changelog conflict

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Merge main to resolve PR 8241 changelog conflict

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Merge main to resolve PR 8241 changelog conflict

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Shubham Padkonde (Shubham-Padkonde) commented Sep 21, 2026

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