unable to get One to Many (owner -> cars ) link from jhipster generated entities

Question

Using jhipster I have created application which is working fine then I have created 'A bi-directionnal one-to-many relationship', Owner to Car. That is also working fine but I could not able to figure out the way how all the cars will be displayed from Owner screen from the generated entities. From Cars screen if I select 'Owner', relevant owner is getting displayed. Similarly from Owner screen if I select Owner Id, I want to display the list of his cars. But from my generated entity screens I did not find this feature. However the jhipster document says " we had a bi-directionnal relationship: from a Car instance you could find its owner, and from a Owner instance you could get all of its cars" . In car screen I have a field for owner but in owner screen I don't have any link to display all the cars of a particular owner as stated above "from a Owner instance you could get all of its cars". How can I achieve it? From the document I feel this feature is in built from jhipster generated entities however I could not able to figure it out, can any one give sample code for Angular js and Spring Rest call to display all the cars of a particular owner from owners page (i.e., from http://localhost:8080/#/owners).

Owner.java

@Entity
@Table(name = "OWNER")
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class Owner implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(name = "name")
    private String name;

    @Column(name = "age")
    private Integer age;

    @OneToMany(mappedBy = "owner")
    @JsonIgnore
    @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
    private Set<Car> cars = new HashSet<>();


}

OwnerResource.java

    @RestController
    @RequestMapping("/api")
    public class OwnerResource {    
        private final Logger log = LoggerFactory.getLogger(OwnerResource.class);    
        @Inject
        private OwnerRepository ownerRepository;    

        @RequestMapping(value = "/owners",
                method = RequestMethod.POST,
                produces = MediaType.APPLICATION_JSON_VALUE)
        @Timed
        public ResponseEntity<Owner> create(@RequestBody Owner owner) throws URISyntaxException {
            log.debug("REST request to save Owner : {}", owner);
            if (owner.getId() != null) {
                return ResponseEntity.badRequest().header("Failure", "A new owner cannot already have an ID").body(null);
            }
            Owner result = ownerRepository.save(owner);
            return ResponseEntity.created(new URI("/api/owners/" + result.getId()))
                    .headers(HeaderUtil.createEntityCreationAlert("owner", result.getId().toString()))
                    .body(result);
        }

       @RequestMapping(value = "/owners",
            method = RequestMethod.PUT,
            produces = MediaType.APPLICATION_JSON_VALUE)
        @Timed
        public ResponseEntity<Owner> update(@RequestBody Owner owner) throws URISyntaxException {
            log.debug("REST request to update Owner : {}", owner);
            if (owner.getId() == null) {
                return create(owner);
            }
            Owner result = ownerRepository.save(owner);
            return ResponseEntity.ok()
                    .headers(HeaderUtil.createEntityUpdateAlert("owner", owner.getId().toString()))
                    .body(result);
        }

       @RequestMapping(value = "/owners",
                method = RequestMethod.GET,
                produces = MediaType.APPLICATION_JSON_VALUE)
        @Timed
        public ResponseEntity<List<Owner>> getAll(@RequestParam(value = "page" , required = false) Integer offset,
                                      @RequestParam(value = "per_page", required = false) Integer limit)
            throws URISyntaxException {
            Page<Owner> page = ownerRepository.findAll(PaginationUtil.generatePageRequest(offset, limit));
            HttpHeaders headers = PaginationUtil.generatePaginationHttpHeaders(page, "/api/owners", offset, limit);
            return new ResponseEntity<>(page.getContent(), headers, HttpStatus.OK);
        }

 @RequestMapping(value = "/owners/{id}",
                method = RequestMethod.GET,
                produces = MediaType.APPLICATION_JSON_VALUE)
        @Timed
        public ResponseEntity<Owner> get(@PathVariable Long id) {
            log.debug("REST request to get Owner : {}", id);
            return Optional.ofNullable(ownerRepository.findOne(id))
                .map(owner -> new ResponseEntity<>(
                    owner,
                    HttpStatus.OK))
                .orElse(new ResponseEntity<>(HttpStatus.NOT_FOUND));
        }

    }

OwnerRepository.java

/**
 * Spring Data JPA repository for the Owner entity.
 */
public interface OwnerRepository extends JpaRepository<Owner,Long> {    


}

The basic crud operation is working fine for Owner. But now I need to get all cars of a particular owner for that I need to add one rest call entry in OwnerResource.java and a method entry in OwneRepository.java. I tried different ways but getting many errors and is not working. The following is what I tried.

In OwnerRepository.java

Owner findAllByOwnerId(Long id);//But eclipse shows error here for this method

In OwnerResource.java

//Get All Cars
    @RequestMapping(value = "/{id}/cars",
            method = RequestMethod.GET,
            produces = MediaType.APPLICATION_JSON_VALUE)
    @Timed
    public ResponseEntity<Owner> getAll(@PathVariable Long id) {
        log.debug("REST request to get All Cars of the Owner : {}", id);
        return Optional.ofNullable(ownerRepository.findAllByOwnerId(id))
            .map(owner -> new ResponseEntity<>(
                owner,
                HttpStatus.OK))
            .orElse(new ResponseEntity<>(HttpStatus.NOT_FOUND));
    }

I need fix for this.

Answer 1

You could try this

In owner.java change

@OneToMany(mappedBy = "owner")
@JsonIgnore
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
private Set<Car> cars = new HashSet<>();

to

@OneToMany(mappedBy = "owner", fetch = FetchType.EAGER)
@JsonIgnoreProperties({"owner"})
private Set<Car> cars = new HashSet<>();

and similary in car.java

@ManyToOne
@JoinColumn(name = "owner_id")
@JsonIgnoreProperties({"cars"})
private Owner owner;

I'm new to spring as well but this helped me when I had a similar problem.