How to consume Spring Hateoas CollectionModel using WebClient? - spring

Question

I figued out how to consume an EntityModel, but so far am unable to consume a CollectionModel (Spring code is using Groovy)
My Class:
#Relation(value = "person", collectionRelation = "people")
class Person {
long id
String firstName
String lastName
}
My Controller:
CollectionModel<Person> getPeople() {
Person person = new Person(
id: 2L,
firstName: 'Mark',
lastName: 'Hamil'
)
Collection<Person> people = Collections.singleton(person)
CollectionModel.of(people)
}
Then I created a service to consume the output of the controller:
CollectionModel<Person> model= this.webClient.get().uri('localhost:8080/api/people')
.retrieve()
.bodyToMono(new TypeReferences.CollectionModelType<Person>())
.block()
List<Person> people = model.content
But the model is blank. I'm not sure what I'm doing incorrectly.
Here is the raw output of localhost:8080/api/people
{
"_embedded": {
"people": [
{
"id": 2,
"firstName": "Mark",
"lastName": "Hamil"
}
]
}
}

Answer 1

After posting over at https://gitter.im/spring-projects/spring-hateoas# and getting some insight, I was able to get this working. Note this is using Groovy.
First, in the controller I made sure the produces was set for hal:
#RequestMapping(method = RequestMethod.GET, produces = "application/hal+json")
CollectionModel<Person> getPeople() {
Link link = linkTo(PersonController).withSelfRel()
List<EntityModel> entityModelList = [this.getPerson()]
}
Where this.getPerson() is:
EntityModel<Person> getPerson() {
Person person = new Person(
id: 2L,
firstName: 'Mark',
lastName: 'Hamil'
)
Link link = linkTo(PersonController).slash(person.id).withSelfRel()
EntityModel<Person> personEntityModel = EntityModel.of(person, link)
personEntityModel
}
Then in the calling api:
Mono<CollectionModel<EntityModel<Person>>> personCollectionModel = this.webClient
.get()
.uri('localhost:8080/uswf-api/people')
.accept(MediaTypes.HAL_JSON)
.exchange()
.flatMap { response ->
if (response.statusCode().isError()) {
System.out.println('Error')
} else {
response.bodyToMono(new ParameterizedTypeReference<CollectionModel<EntityModel<Person>>>() {})
}
}
Then I can use this result by subscribing to the result:
personCollectionModel.subscribe( { collectionModel -> collectionModel.content })