如何通过具有弹簧数据休息的备用键公开实体

Question

Spring-data-rest does a great job exposing entities via their primary key for GET , PUT and DELETE etc. operations.

/myentityies/123

It also exposes search operations.

/myentities/search/byMyOtherKey?myOtherKey=123

In my case the entities have a number of alternate keys. The systems calling us, will know the objects by these IDs, rather than our internal primary key. Is it possible to expose the objects via another URL and have the GET , PUT and DELETE handled by the built-in spring-data-rest controllers?

/myentities/myotherkey/456

We'd like to avoid forcing the calling systems to have to make two requests for each update.

I've tried playing with @RestResource path value, but there doesn't seem to be a way to add additional paths.

Answer 1

I finally figured out how to do this!

Add an implementation of BackendIdConverter to your Spring context.

@Component
public class BackendIdConverterImpl implements BackendIdConverter {

  @Override
  public boolean supports(Class<?> delimiter) {
    return true; // Always convert.
  }

  @Override
  public Serializable fromRequestId(String id, Class<?> entityType) {
    // Convert from the external key to your internal key.
  }

  @Override
  public String toRequestId(Serializable id, Class<?> entityType) {
    // Convert from the internal key to your external key.
  }

}

Answer 2

You think in URI, and Spring Data Rest in designed to think in relations.

There is no problem in declaring another controller, using @RepositoryRestController mapped on

/myentities/myotherkey/{otherKey}

but then, how will it be discovered by the client application ? To be consistent, you'll have to add a link to this controller in your resource mapping, with a custom ResourceProcessor<Resource<Myentity>> .

But no pre-made stuff here. In a REST environment, the ID of an entity is supposed to be its URI. If you want to have another paradigm, then you will have to adapt it yourself, unfortunately.