Api Platform Dto Resources (Symfony)

Use when

• The #[ApiResource] class must be the API contract, decoupled from the Doctrine entity.
• Entity and API fields differ in name or format (rename, formatted price, computed value).
• Create, update, or list operations need their own input or output shape.
• Migrating code that relied on DataTransformerInterface, which no longer exists.

Default workflow

1. Require symfony/object-mapper and set stateOptions: new Options(entityClass: ...) on the DTO resource.
2. Bind the DTO and the entity with #[Map(source: ...)] and #[Map(target: ...)], and use #[Map(transform: ...)] for computed fields.
3. For distinct shapes, create input and output classes and wire them with input: and output: on each operation.
4. When mapping needs real logic, write a custom ProcessorInterface that calls ObjectMapperInterface::map().
5. Test each operation: payload in, response shape out.