Return IDs in JSON response from Spring Data REST - spring-boot

Question

I've got an entity
#Entity
#Table(name = "books")
public class Book {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
#Column(name = "id", unique = true, nullable = false)
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
#Column(name = "name")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
I initialize it like this
#PostConstruct
public void init() {
List<String> newFiles = this.listFiles();
newFiles.forEach(filename -> {
Book book = new Book();
book.setName(filename);
dbRepository.save(book);
});
}
If I set the result of save to an instance of Book, I can get the id and it is not null—so id is created fine.
I defined a repository
#RepositoryRestResource
public interface IBooksRepository extends CrudRepository<Book, Long> {
}
which I'd like to use to get and set data into the books table in the database.
When I try to access my repository rest using curl localhost:8080/books, I get this response
{
"_embedded":{
"books":[
{
"name":"simple-file.txt",
"_links":{
"self":{
"href":"http://localhost:8080/books/1"
},
"book":{
"href":"http://localhost:8080/books/1"
}
}
}
]
},
"_links":{
"self":{
"href":"http://localhost:8080/books"
},
"profile":{
"href":"http://localhost:8080/profile/books"
}
}
}
The books element returns name only. How can I make it return id too, on the same level as name?

Answer 1

Spring Data Rest hides the ID by default, in order to have it in the JSON you have to manually configure that for your entity. Depending on your spring version you can either provide your own configuration (old):
#Configuration
public class ExposeEntityIdRestConfiguration extends RepositoryRestMvcConfiguration {
#Override
protected void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
config.exposeIdsFor(Book.class);
}
}
...or register a RepositoryRestConfigurer (current):
#Component
public class ExposeEntityIdRestMvcConfiguration extends RepositoryRestConfigurerAdapter {
#Override
public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
config.exposeIdsFor(Book.class);
}
}
See the Spring Data Rest documentation for more details.

Answer 2

The accepted answer overrides a deprecated method. Here's the updated version:
#Component
public class RestConfig implements RepositoryRestConfigurer {
#Override
public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config, CorsRegistry cors) {
config.exposeIdsFor(Book.class);
}
}
An alternative approach is to implement RepositoryRestConfigurer in your #SpringBootApplication annotated class:
#SpringBootApplication
public class MyApplication implements RepositoryRestConfigurer {
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
#Override
public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config, CorsRegistry cors) {
config.exposeIdsFor(Book.class);
}
}

Answer 3

There is now a static method RepositoryRestConfigurer.withConfig that does the same thing as above. See javadoc:
Convenience method to easily create simple {#link RepositoryRestConfigurer} instances that solely want to tweak the {#link RepositoryRestConfiguration}.
I found the usage in one of their integration tests
So the following approach would be more up to date as of now:
#Bean
public RepositoryRestConfigurer repositoryRestConfigurer()
{
return RepositoryRestConfigurer.withConfig(config -> {
config.exposeIdsFor(Book.class);
});
}

Answer 4

#Component
public class RestConfig implements RepositoryRestConfigurer {
#Override
public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
config.exposeIdsFor(Book.class);
//config.exposeIdsFor(Library.class);
}
}

Answer 5

This is a solution which works for all entities
#Autowired
private EntityManager entityManager;
#Bean
public RepositoryRestConfigurer repositoryRestConfigurer() {
return RepositoryRestConfigurer.withConfig(config -> config.exposeIdsFor(entityManager.getMetamodel().getEntities().stream().map(Type::getJavaType).toArray(Class[]::new)));
}

Answer 6

This is a good way to go.
#Projection(name = "customBook", types = { Book.class })
public interface CustomBook {
#Value("#{target.id}")
long getId();
}
credit: https://www.baeldung.com/spring-data-rest-projections-excerpts