How do I avoid n+1 queries with Spring Data Rest?

Question

Question. How do I avoid n+1 queries with Spring Data REST?

Background. When querying Spring Data REST for a list of resources, eac

Answer 1

Spring Data REST will only create the representation you describe if the serializer that is configured inside the Jackson ObjectMapper is triggered by seeing a PersistentEntityResource, which is a special kind of Resource that is used inside Spring Data REST.

If you create a ResourceProcessor> and return a new Resource(origResource.getContent(), origResource.getLinks()), then the default Spring Data REST serialization machinery will not be triggered and Jackson's normal serialization rules will apply.

Note, however, that the reason Spring Data REST does associations the way it does is because it's very difficult to arbitrarily stop traversing an object graph when serializing to JSON. By handling associations the way it does, it guarantees that the serializer won't start traversing an object graph that is N levels deep and become much slower in performance and in the performance of the representation going over-the-wire.

Ensuring that Jackson does not try to serialize a PersistentEntityResource, which is what it's doing in the default configuration, will ensure that none of the Spring Data REST handling of associations is triggered. The down side to this, of course, is that none of Spring Data REST's helpers will be triggered. If you still want links to the associated resources, you'll have to make sure you create those yourself and add them to the outgoing plain Resource.