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fix: recurse into OpenAPI 3.1 fields in transformOpenAPIToJSONSchema#1121

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reuvenharrison wants to merge 14 commits intogetkin:masterfrom
oasdiff:fix/transform-openapi-to-jsonschema-recursion
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fix: recurse into OpenAPI 3.1 fields in transformOpenAPIToJSONSchema#1121
reuvenharrison wants to merge 14 commits intogetkin:masterfrom
oasdiff:fix/transform-openapi-to-jsonschema-recursion

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Summary

  • Fix transformOpenAPIToJSONSchema to recurse into OpenAPI 3.1 / JSON Schema 2020-12 schema fields

Problem

When using the JSON Schema 2020-12 validator (EnableJSONSchema2020()), the transformOpenAPIToJSONSchema function converts OpenAPI 3.0-isms (like nullable: true) into JSON Schema 2020-12 equivalents (like type arrays). However, it only recursed into pre-3.1 fields:

  • properties, additionalProperties, items, not
  • oneOf, anyOf, allOf

Schemas nested inside OpenAPI 3.1 fields were not transformed, so an OpenAPI 3.0-style nullable: true inside e.g. prefixItems would not be converted, causing incorrect validation results.

Solution

Add recursion into all OpenAPI 3.1 / JSON Schema 2020-12 fields:

  • Single schema fields: contains, propertyNames, unevaluatedItems, unevaluatedProperties
  • Schema arrays: prefixItems
  • Schema maps: patternProperties, dependentSchemas

Also consolidated the properties map iteration with patternProperties and dependentSchemas into a single loop to reduce duplication.

Related

Follow-up to PR #1114 (OpenAPI 3.1 support).

Test plan

  • New test TestJSONSchema2020Validator_TransformRecursesInto31Fields with 7 sub-tests covering each field type
  • Each test uses nullable: true in a nested schema to verify the transform recurses correctly
  • All existing tests pass

🤖 Generated with Claude Code

Chance Kirsch and others added 14 commits October 2, 2025 08:46
The implementation provides complete OpenAPI 3.1 specification compliance while maintaining 100% backward compatibility with OpenAPI 3.0.

## What Was Implemented

### 1. Schema Object Extensions (openapi3/schema.go)

Added full JSON Schema 2020-12 support with new fields:

- **`Const`** - Constant value validation
- **`Examples`** - Array of examples (replaces singular `example`)
- **`PrefixItems`** - Tuple validation for arrays
- **`Contains`, `MinContains`, `MaxContains`** - Array containment validation
- **`PatternProperties`** - Pattern-based property matching
- **`DependentSchemas`** - Conditional schema dependencies
- **`PropertyNames`** - Property name validation
- **`UnevaluatedItems`, `UnevaluatedProperties`** - Unevaluated keyword support
- **Type arrays** - Support for `["string", "null"]` notation

### 2. Document-Level Features (openapi3/openapi3.go)

- **`Webhooks`** - New field for defining webhook callbacks (OpenAPI 3.1)
- **`JSONSchemaDialect`** - Specifies default JSON Schema dialect
- **Version detection methods**:
  - `IsOpenAPI3_0()` - Returns true for 3.0.x documents
  - `IsOpenAPI3_1()` - Returns true for 3.1.x documents
  - `Version()` - Returns major.minor version string

### 3. License Object (openapi3/license.go)

- **`Identifier`** - SPDX license expression (alternative to URL)

### 4. Info Object (openapi3/info.go)

- **`Summary`** - Short summary of the API (OpenAPI 3.1)

### 5. Types Helper Methods (openapi3/schema.go)

New methods for working with type arrays:

- `IncludesNull()` - Checks if null type is included
- `IsMultiple()` - Detects type arrays (OpenAPI 3.1 feature)
- `IsSingle()` - Checks for single type
- `IsEmpty()` - Checks for unspecified types

### 6. JSON Schema 2020-12 Validator (openapi3/schema_jsonschema_validator.go)

A new opt-in validator using [santhosh-tekuri/jsonschema/v6](https://github.com/santhosh-tekuri/jsonschema):

- Full JSON Schema Draft 2020-12 compliance
- Automatic OpenAPI → JSON Schema transformation
- Converts OpenAPI 3.0 `nullable` to type arrays
- Handles `exclusiveMinimum`/`exclusiveMaximum` conversion
- Comprehensive error formatting
- Fallback to built-in validator on compilation errors
…d formatting and correcting the version logic
The ResolveRefsIn function was not resolving $ref references inside
webhooks, causing Schema.Value to be nil when a webhook operation
referenced a component schema.

This adds webhook ref resolution after the paths loop, using the same
resolvePathItemRef function since webhooks contain PathItem objects.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
In OpenAPI 3.0 (JSON Schema draft-04), exclusiveMinimum/exclusiveMaximum
are booleans that modify minimum/maximum values.

In OpenAPI 3.1 (JSON Schema 2020-12), they are numbers representing
the actual exclusive bounds.

This change introduces ExclusiveBound type that can hold either:
- Bool: for OpenAPI 3.0 style boolean modifier
- Value: for OpenAPI 3.1 style numeric bound

The validation and marshaling logic handles both formats correctly.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
The OpenAPI-to-JSON-Schema transformation only recursed into pre-3.1
fields (properties, additionalProperties, items, not, oneOf, anyOf,
allOf). Nested schemas inside 3.1 fields with OpenAPI 3.0-isms like
nullable:true were not converted, causing incorrect validation.

This adds recursion into: prefixItems, contains, patternProperties,
dependentSchemas, propertyNames, unevaluatedItems,
unevaluatedProperties.

Also consolidates the properties/patternProperties/dependentSchemas
map iteration into a single loop.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@reuvenharrison
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Superseded by #1125 which consolidates all OpenAPI 3.1 PRs into a single PR.

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3 participants