ModelMapper can map DTO to Entity, but not back again - spring

Question

Seeing some odd behavior using ModelMapper. To demonstrate I have an AnimalDto object that looks like this:
#SuperBuilder()
#Getter
#NoArgsConstructor
#ToString
public class AnimalDto {
/**
* Type of the animal
*/
private String animalType;
/**
* Description of animal
*/
private JsonNode animalDesc;
}
Then I have an AnimalEntity that resembles this Dto object, and is able to be saved in the DB:
#Getter
#Setter
#NoArgsConstructor
#TypeDef(name = "jsonb", typeClass = JsonBinaryType.class)
#ToString
public class AnimalEntity {
/**
* Animal id for this animal
*/
#Id
private UUID id = UUID.randomUUID();
/**
* Type of animal
*/
#Column(name = "animal_type")
private String animalType;
/**
* JSON which describes the animal
*/
#Type(type = "jsonb")
#Column(name = "animal_desc")
private JsonNode animalDesc;
}
When I use ModelMapper to map between the objects I am able to successfully convert from a AnimalDto to an AnimalEntity:
JsonNode animalDesc = objectMapper.convertValue("{\"desc\": \"small penguin\"}", JsonNode.class);
AnimalDto animalDto = AnimalDto.builder().animalType("penguin").animalDesc(animalDesc).build();
AnimalEntity animalEntity = modelMapper.map(animalDto, AnimalEntity.class);
System.out.println(animalEntity);
The output will be expected:
AnimalEntity(id=47066e09-3a40-4a85-89fa-4befabdf03fa, animalType=penguin, animalDesc="{ \"desc\": \"small penguin\"}")
However, if I do the same back again:
AnimalDto testDto = modelMapper.map(animalEntity, AnimalDto.class);
System.out.println(testDto)
Output will be:
AnimalDto(animalType=null, animalDesc=null)
When I am expecting:
AnimalDto(animalType=penguin, animalDesc="{ \"desc\": \"small penguin\"}")
Why is it able to map one-way, but not the way back?
EDIT:
Fixed Code error
EDIT 2: The issue is that the Dto is missing the Setters. It can create an instance of the object but cannot set any of the fields. You need a public setter for all the fields you want to be able to set. See: link