Child object is null during Jackson serialization? - json

Question

I captured the json response and I see that it is
{"page":"1","total":"2","records":"15","rows":[{"id":1,"firstName":"John","lastName":"Smith","username":"john","password":"21232f297a57a5a743894a0e4a801fc3","role":null},{"id":2,"firstName":"Jane","lastName":"Adams","username":"jane","password":"ee11cbb19052e40b07aac0ca060c23ee","role":null},
My User and Role classes are super simple, so I think I must be overlooking something trivial.
#Entity(name="user")
public class User implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String firstName;
private String lastName;
#Column(unique=true)
private String username;
private String password;
#JsonIgnore
#OneToMany(mappedBy="user", cascade={CascadeType.PERSIST, CascadeType.MERGE},fetch =FetchType.EAGER)
private List<Role> roles = new ArrayList<Role>();
public List<Role> getRoles() {
return roles;
}
public void setRoles(List<Role> roles) {
this.roles = roles;
}
#ManyToOne
private Role role;
public User() {}
public User(String username, String password, String firstName, String lastName, Role role) {
this.username = username;
this.password = password;
this.firstName = firstName;
this.lastName = lastName;
this.role = role;
}
public User(String username, String firstName, String lastName, Role role) {
this.username = username;
this.firstName = firstName;
this.lastName = lastName;
this.role = role;
}
public User(String username) {
this.username = username;
}
public Long getId() {
return id;
}
public void setId(Long 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 getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Role getRole() {
return role;
}
public void setRole(Role role) {
this.role = role;
}
}
#Entity(name="role")
public class Role implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#JsonIgnore
#ManyToOne
#JoinColumn (name = "user_id", nullable= true)
private User user;
private Integer role;
public Role() {}
public Role(Integer role) {
this.role = role;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
public Integer getRole() {
return role;
}
public void setRole(Integer role) {
this.role = role;
}
}
I tried also
#JsonUnwrapped #ManyToOne private Role role;
but that's even worse because in this case my json doesn't have the role at all.
{"id":1,"firstName":"John","lastName":"Smith","username":"john","password":"21232f297a57a5a743894a0e4a801fc3"},

Answer 1

I was manipulating the object incorrectly before passing it back as a response due to a complex legacy relationship requirement i.e. User has a role and roles.
#JsonUnwrapped can only unwrap if there are properties in the child object, so it works as expected.