[go] add useAnyOfAllMatches option for spec-compliant anyOf unmarshalling

[AriehSchneier]

Description

The anyOf specification requires that data validates against one or more of the subschemas. The current generated UnmarshalJSON for anyOf schemas returns on the first successful match, which means:

• Subsequent schemas are never attempted
• Multiple simultaneously-matching fields are not populated
• Results are order-dependent (schema order in the spec determines which field wins)

This is the same pattern used by C# and Java generators, but it is not spec-compliant.

Fix

Add a new generator option useAnyOfAllMatches (default: false) that, when enabled, tries all anyOf schemas and populates every field whose schema matches. Returns nil if at least one schema matched, or an error if none did.

The default remains false to preserve backwards compatibility with existing generated code.

Changes

• GoClientCodegen.java: add USE_ANYOF_ALL_MATCHES constant, useAnyOfAllMatches field, CLI option, processOpts handling, and getter
• model_anyof.mustache: {{#useAnyOfAllMatches}} block emits a try-all + match-count loop; {{^useAnyOfAllMatches}} preserves existing first-match behaviour
• GoClientOptionsProvider / GoClientOptionsTest: coverage for the new option
• anyof_multiple_matches.yaml: test spec with two schemas (SpecA has name, SpecB has value) that can simultaneously match the same payload under a Contact anyOf
• GoClientCodegenTest: two new tests verifying default behaviour is unchanged and new behaviour works correctly

PR checklist

• Read the contribution guidelines
• If contributing template-only or documentation-only changes which will change sample output, build the project before running ./bin/generate-samples.sh
• File the PR against the correct branch
• Add test(s) — two new tests in GoClientCodegenTest plus options test coverage
• Generate samples for any changed language — N/A (behind opt-in flag, default unchanged)

---

Summary by cubic

Adds useAnyOfAllMatches to the Go generator for spec-compliant anyOf handling. When enabled, unmarshal tries all subschemas and populates every matching field; marshal merges object fields, errors on conflicting values, and falls back to the first non-object value. Default remains first-match.

• New Features

  • New CLI/config option useAnyOfAllMatches (default: false): unmarshal tries all anyOf schemas; succeeds if at least one matches; populates all matching fields. Marshal merges object keys from all non-nil schemas, errors on conflicting values for the same key, and falls back to the first non-object value.
  • model_anyof.mustache: adds try-all loop in UnmarshalJSON and merged output with conflict detection and primitive fallback in MarshalJSON when enabled; preserves current first-match paths otherwise.
  • GoClientCodegen: adds option constant, CLI flag, processing, and getter. Tests cover default vs. enabled behavior, object merge with conflict detection (anyof_clashing_fields.yaml), primitive fallback (anyof_primitive_schemas.yaml), and multiple matches (anyof_multiple_matches.yaml).

• Migration

  • Opt in via --additional-properties useAnyOfAllMatches=true. Default behavior is unchanged.

^{Written for commit e0a11c7. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 6 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="modules/openapi-generator/src/main/resources/go/model_anyof.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/go/model_anyof.mustache:62">
P1: `useAnyOfAllMatches` can populate multiple anyOf schema fields, but `MarshalJSON` still returns only the first non-nil schema, causing silent lossy, order-dependent re-serialization.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

1 issue found across 2 files (changes from recent commits).

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="modules/openapi-generator/src/main/resources/go/model_anyof.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/go/model_anyof.mustache:112">
P2: useAnyOfAllMatches silently drops non-object anyOf variants during MarshalJSON because it only treats map-unmarshal success as data, leading to data loss or nil output for primitive/array matches.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}