Why does RestTemplate not bind response representation to PagedResources?

Question

I am using spring-data-rest to expose entities as (paged) rest resources. Everything works fine, but when I request data via RestTemplate, I get an useless HATEOAS JSON (which I didn't ask for). The JSON seems to be a PagedResources. I could live with that, but the JSON isn't converted into an object correctly. There is no content inside.

Repository:

@RepositoryRestResource(collectionResourceRel = "people", path = "people") public interface PersonRepository extends PagingAndSortingRepository<Person, Long> {     List<Person> findByLastName(@Param("name") String name); } 

Client:

public List<Person> getPersons() {     RestTemplate rt = new RestTemplate();     System.out.println(rt.getForObject(URL, PagedResources.class).getContent().size());     System.out.println(rt.getForObject(URL, PagedResources.class).getLinks().size());     System.out.println(rt.getForObject(URL, PagedResources.class).getMetadata().getTotalElements());     return new ArrayList<Person>(rt.getForObject(URL, PagedResources.class).getContent()); // <-- empty } 

System.out:

0 // getContent().size() 4 // getLinks().size() 2 // getTotalElements() 

curl:

C:\...>curl http://localhost:8080/spring-jsf-rest/rest/people {   "_links" : {     "self" : {       "href" : "http://localhost:8080/spring-jsf-rest/rest/people{?page,size,sort}",       "templated" : true     },     "search" : {       "href" : "http://localhost:8080/spring-jsf-rest/rest/people/search"     }   },   "_embedded" : {     "people" : [ {       "firstName" : "John",       "lastName" : "Rambo",       "_links" : {         "self" : {           "href" : "http://localhost:8080/spring-jsf-rest/rest/people/1"         }       }     }, {       "firstName" : "Chuck",       "lastName" : "Norris",       "_links" : {         "self" : {           "href" : "http://localhost:8080/spring-jsf-rest/rest/people/2"         }       }     } ]   },   "page" : {     "size" : 20,     "totalElements" : 2,     "totalPages" : 1,     "number" : 0   } } 

It seems like _embedded is not mapped correctly to content?!

Answer 1

As you've discovered correctly, PagedResources does not have an _embedded property, that's why you don't get the content property populated.

This dilemma can be solved in two different ways:

1. Providing a type that matches the representation in the first place. Thus, craft a custom class and either stick to the property names of the representation or customize it using Jackson annotations etc.

2. Set up a custom MappingJackson2HttpMessageConverter and customize the ObjectMapperto get the Jackson2HalModule configured that Spring HATEOAS ships out of the box.

   ObjectMapper mapper = new ObjectMapper(); mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false); mapper.registerModule(new Jackson2HalModule());  MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter(); converter.setSupportedMediaTypes(MediaType.parseMediaTypes("application/hal+json")); converter.setObjectMapper(mapper);  RestTemplate template = new RestTemplate(Collections.<HttpMessageConverter<?>> singletonList(converter));