Why am i getting a jackson No serializer found error for JPA entity on OneToOne mapping?

Question

I created two JPA entity classes to represent the following tables:

I think that the one-to-one relationship I setup is incorrrect because I am getting the error:

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class org.hibernate.proxy.pojo.bytebuddy.ByteBuddyInterceptor and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: ca.allauto.ups.model.Vehicle["model"]->ca.allauto.ups.model.VehicleModel$HibernateProxy$zuv5wN1w["hibernateLazyInitializer"])

Here is the vehicle class:

package ca.allauto.ups.model;

@Entity
@Table(name = "vehicle")
@Data
public class Vehicle {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="id")
    private Long id;
    
    @Column(name="year")
    private short year;
    
    @OneToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "model_id", referencedColumnName = "id")
    private VehicleModel model;
    
    @Column(name="doors")
    private DoorsEnum doors;
    
    @Column(name="vehicle_type")
    private VehicleTypeEnum vehicleType;
    
    @Column(name="color")
    private ColorEnum color;
    
    @Column(name="odometer")
    private Long odometer;
    
    @Column(name="kms_miles")
    private KmsOrMilesEnum kmsOrMiles;
    
    @Column(name="transmission")
    private TransmissionEnum transmission;
    
    @Column(name="vin")
    private String vin;
}

And this is the VehicleModel:

@Entity
@Table(name = "vehicle_model")
@Data
public class VehicleModel {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="id")
    private Long id;
    
    @Column(name="model")
    private String model;
    
    // I took this out because it was causing the server to crash
    //@OneToOne(mappedBy = "model")
   // private Vehicle vehicle;
    
}

I would like for the vehicle class to be returned so that it includes the vehicle model as a nested object, as in:

{
  id: 1,
  year: 2022,
  model: {
    id: 2,
    model: "Toyota Prius"
  },
  doors: 4,
  vehicle_type: "Hatchback",
  color: "Blue",
  etc...
}

Any ideas what I'm doing wrong?

Answer 1

The default Jackson serializer does not like it when you use nested objects. The following code worked for me when it came to serializing nested objects:

@GetMapping(path = "/your/path")
public String getNestedObject() {
    Vehicle myV = new Vehicle(/*init*/);
    ObjectMapper mapper = new ObjectMapper();
    mapper.setVisibiliy(PropertyAccessor.ALL, 
    JsonAutoDetect.Visibility.ANY);
    String json = mapper.writeValueAsString(myV);
    return json;
}