How to remove the "_embedded" property in Spring HATEOAS - spring

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

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 3

Adding this Accept header to the request:
Accept : application/x-spring-data-verbose+json

Answer 4

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.

Answer 5

What you're describing in the produced and expected results are semantically different things. The former thing is the HAL representation of a Collection<Technology>. The latter, which you expect is the representation of:
class Wrapper {
Resources<Technology> technologies;
}
Note how this is how we actually create the top level technologies property that you would like to see in your response. You don't create any of the latter in your controller. A top-level Resourcesinstance is basically a collection and the only way to represent a top-level collection in HAL is _embedded. Apparently you don't want that but that's what you have written in your controller method.
Assuming you have Wrapper, something like this should work (untested):
Wrapper wrapper = new Wrapper(assembler.toCollectionModel(technologies);
EntityModel<Wrapper> model = EntityModel.of(wrapper);
model.add(linkTo(…));
PS: As of Spring HATEOAS 1.0, Resources is CollectionModel and Resourceis EntityModel.

Answer 6

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 7

For latest versions in Spring RepositoryRestConfigurer doesn't include the method public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) you'd need to override the default method on RepositoryRestConfigurer which include cors parameter.
public class RestConfiguration implements RepositoryRestConfigurer {
public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config, CorsRegistry cors) {
config.setDefaultMediaType(MediaType.APPLICATION_JSON);
config.useHalAsDefaultJsonMediaType(false);
}
}