Spring Boot: Saving a one to many json request, foreign key is not saved automatically

Question

I have 2 entities, Role and Resource. A role can have many resources.

@Entity
public class Resource {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;

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

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

private String email;

@ManyToOne
@JoinColumn(name="roleId", nullable = false)
private Role role;

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getFirstName() {
    return firstName;
}

public void setFirstName(String firstName) {
    this.firstName = firstName;
}

public String getLastName() {
    return lastName;
}

public void setLastName(String lastName) {
    this.lastName = lastName;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}


public Role getRole() {
    return role;
}

public void setRole(Role role) {
    this.role = role;
}

}

@Entity
public class Role {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;

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

@OneToMany(mappedBy = "role", cascade = CascadeType.ALL)
private List<Resource> resources;

public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}

public String getRoleName() {
    return roleName;
}
public void setRoleName(String roleName) {
    this.roleName = roleName;
}
public List<Resource> getResources() {
    return resources;
}
public void setResources(List<Resource> resources) {
    this.resources = resources;
}

}

I'm trying to save a Role object that has a resource in it. This is the body of my json in postman.

{
"roleName" : "Business Analyst",
"resources" : [{
    "firstName" : "John",
    "lastName" : "Doe",
    "email" : "John@Doe.com"
}]
}

http post call in postman:

http://localhost:8080/app/admin/roles/role

Role Controller

@RestController
@RequestMapping(value="/admin/roles")
public class RoleController {
@Autowired 
private RoleService roleService;

private static final Logger log = LoggerFactory.getLogger(RoleController.class);

@RequestMapping(value="/role", method = RequestMethod.POST)
public ResponseEntity<?> addRole(@RequestBody Role role, UriComponentsBuilder ucBuilder){
    log.info("Adding Role {}" + role);
    log.info("Adding Rolename:" + role.getRoleName());

    roleService.addRole(role);
    HttpHeaders headers = new HttpHeaders();
    headers.setLocation(ucBuilder.path("/admin/roles/role/{id}").buildAndExpand(role.getId()).toUri());
    return new ResponseEntity<String> (headers,HttpStatus.CREATED);
}

@RequestMapping(value="role", method = RequestMethod.GET)
public ResponseEntity<List<Role>> listAllRoles(){
    List<Role> roles = roleService.getAllRoles();
    return new ResponseEntity<List<Role>>(roles, HttpStatus.OK);
}

}

RoleRepository

public interface RoleRepository extends CrudRepository<Role, Integer> {

}

RoleService

public interface RoleService {

public void addRole(Role role);


}

RoleServiceImpl

@Service
public class RoleServiceImpl implements RoleService {

@Autowired
private RoleRepository roleRepository;

@Override
public void addRole(Role role) {
    roleRepository.save(role);
}
}

Whats happening is, the role Business Analyst gets save in the roleName field of Role table. The id of the said row is auto generated. At the same time, the resource with firstName = John, lastName = Doe and email = John@Doe.com gets save in the Resource table.

However, the role_id is not being saved automatically in the Resource table so now it is null ( the table Resource has the role_id set to nullable ). I was expecting that when I do the json post, the data will be automatically saved in the Role table and also the Resource table. Both of these are happening except that the role_id is not being saved. What did I miss?

Answer 1

Change addRole like below :

public void addRole(Role role) {


    for(Resource resource: role.getResources()){        
        resource.setRole(role); 
    }

    roleRepository.save(role);
}