How to remove the “_embedded” property in Spring HATEOAS

Question

I'm using Spring Boot and HATEOAS to build a REST API and when my API returns a collection, it is wrapped inside a "_embedded" property, like so:

{
   "_links":{
      "self":{
         "href":"http://localhost:8080/technologies"
      }
   },
   "_embedded":{
      "technologies":[
         {
            "id":1,
            "description":"A",
            "_links":{
               "self":{
                  "href":"http://localhost:8080/technologies/1"
               }
            }
         },
         {
            "id":2,
            "description":"B",
            "_links":{
               "self":{
                  "href":"http://localhost:8080/technologies/2"
               }
            }
         }
      ]
   }
}

I want the response to be like this:

{
   "_links":{
      "self":{
         "href":"http://localhost:8080/technologies"
      }
   },
   "technologies":[
      {
         "id":1,
         "description":"A",
         "_links":{
            "self":{
               "href":"http://localhost:8080/technologies/1"
            }
         }
      },
      {
         "id":2,
         "description":"B",
         "_links":{
            "self":{
               "href":"http://localhost:8080/technologies/2"
            }
         }
      }
   ]
}

My TechnologiesController:

@RestController
@ExposesResourceFor(Technology.class)
@RequestMapping(value = "/technologies")
public class TechnologiesController {
    ...
    @ResquestMapping(method = RequestMethod.GET, produces = "application/vnd.xpto-technologies.text+json")
    public Resources<Resource<Technology>> getAllTechnologies() {
        List<Technology> technologies = technologyGateway.getAllTechnologies();
        Resources<<Resource<Technology>> resources = new Resources<Resource<Technology>>(technologyResourceAssembler.toResources(technologies));
        resources.add(linkTo(methodOn(TechnologiesController.class).getAllTechnologies()).withSelfRel());
        return resources;
    }

The configuration class has the annotation @EnableHypermediaSupport(type = EnableHypermediaSupport.HypermediaType.HAL).

What is the best way to produce the response without the "_embedded"?

Answer 1

As the documentation says

application/hal+json responses should be sent to requests that accept application/json

In order to omit _embedded in you response you'll need to add

spring.hateoas.use-hal-as-default-json-media-type=false

to application.properties.

Answer 2

Adding this Accept header to the request:

Accept : application/x-spring-data-verbose+json

Answer 3

I close HAL feature, because it is hard to using Resources/Resource by restTemplate. I disable this feature by following code:

public class SpringRestConfiguration implements RepositoryRestConfigurer {
    @Override
    public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {

        config.setDefaultMediaType(MediaType.APPLICATION_JSON);
        config.useHalAsDefaultJsonMediaType(false);
    }
}

It work for me. HAL is good if there are more support with restTemplate.

Answer 4

You can use this code in the service

  constructor(
    private httpClient: HttpClient
  ) { }

  retrieveAllStudents(){
    return this.httpClient.get<any[]>(`http://localhost:8080/students`);
  }

This will deal with the _embedded part of Json and extract the desired data.

export class ListStudentsComponent implements OnInit {

 // declaring variables to be used
  student: Student;
  students: Student[];
  message: string;

  // injecting student service into the constuctor
   constructor(
    private studentService: StudentService,
  ) { }

  ngOnInit() {
    this.refreshStudents();
  }
refreshStudents(){
  this.studentService.retrieveAllStudents().subscribe(
     response => {
       console.log(response);
      this.students = response._embedded.students as Student[];
     }
   );
 }

Answer 5

For those who use Spring Data, and consider it as a problem - solution is to set

spring.data.rest.defaultMediaType = application/json

in application properties. There still links will be available, but no _embedded any more.