Add `format: uuid` in the openapi spec generation for UUID strings

[NicoleStrel]

Hello!

Looks like uuid string validation is supported in huma, however when the openapi spec is generated it is not mentioned as a validation requirement for the string with format: uuid. Heres the openapi spec for uuid: https://spec.openapis.org/registry/format/uuid.html

Can we fix openapi generation for string formats (uuid, and any others)?

[leonklingele]

ftr: we might soon get an uuid package in the stdlib! 🥳 golang/go#62026

[philon123]

here is a working example for generating UUID fields in the spec like:

CompanyID:
  type: string
  format: uuid

Excerpt from my code:

// uuidSchema tells Huma to generate {type: string, format: uuid} for uuid.UUID fields.
type uuidSchema struct{}

func (uuidSchema) Schema(r huma.Registry) *huma.Schema {
	return &huma.Schema{Type: huma.TypeString, Format: "uuid"}
}

func getHumaConfig() huma.Config {
	// Register custom formats for fields that just appear as string in regular OpenAPI specs
	registry := huma.NewMapRegistry("#/components/schemas/", huma.DefaultSchemaNamer)
	registry.RegisterTypeAlias(reflect.TypeFor[uuid.UUID](), reflect.TypeFor[uuidSchema]())

	return huma.Config{
		OpenAPI: &huma.OpenAPI{
			OpenAPI: "3.0.4", // openapi-codegen doesn't support 3.1.0 yet
			Info: &huma.Info{
				Title:   "My App",
				Version: "0.1.0",
			},
			Components: &huma.Components{
				Schemas: registry,
				SecuritySchemes: map[string]*huma.SecurityScheme{
					"bearer": {
						Type:         "http",
						Scheme:       "bearer",
						BearerFormat: "JWT",
					},
				},
			},
		},
		OpenAPIPath:   "/openapi",
		DocsPath:      "/docs",
		Formats:       huma.DefaultFormats,
		DefaultFormat: "application/json",
	}
}