Summary

Adds support for OpenAPI 3.x oneOf and anyOf sum types in parameters - path, query, header, and cookie. Previously sum types only worked in request/response bodies.

Note: allOf is for schema merging (intersection), not sum types, and already worked.

Fixes lanej#3

Changes

• Enable sum type validation for parameters in gen_parameters.go
• Add URI encoding using type discriminator switch
• Add URI decoding using fallback strategy (try each variant in order)
• Add test coverage for path and query parameters

Example

Before: Generation failed with "sum type parameter not implemented"

After: Works seamlessly

parameters:
  - name: id
    in: path
    schema:
      anyOf:
        - type: string
          format: uuid
        - type: integer

Generated code:

// Decoding tries each variant in order
var failures []error
if err := decodeAsUUID(); err == nil {
    return nil
} else {
    failures = append(failures, err)
}
if err := decodeAsInt(); err == nil {
    return nil
} else {
    failures = append(failures, err)
}
return errors.Join(failures...)

Testing

• Path parameter with anyOf: [uuid, integer]
• Query parameter with anyOf: [string, integer]
• All existing tests pass