Mapping DTO to existing entity , it is creating new entity - spring

Question

I have Activity class and ActivityDTO as you see below. While saving new entity there is no problem, but if I want to update existing entity, then it is creating new entity although my entity id is from my database entity.
#Getter
#Setter
#Entity
public class Activity implements Serializable {
#Id
#Column(name = "ID")
#GeneratedValue
#SequenceGenerator
private Long id;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval=true)
#JoinTable(name = "ACTIVITY_ATTACHMENT", joinColumns = {
#JoinColumn(name = "ACTIVITY_ID") }, inverseJoinColumns = { #JoinColumn(name = "ATTACHMENT_ID") })
private Set<Attachment> attachments = new HashSet<>();
#Temporal(TemporalType.DATE)
#JsonSerialize(using = CustomJsonDateSerializer.class)
#JsonDeserialize(using = CustomJsonDateDeserializer.class)
#Column(name = "BEGIN_DATE")
private Date beginDate;
#Temporal(TemporalType.DATE)
#JsonSerialize(using = CustomJsonDateSerializer.class)
#JsonDeserialize(using = CustomJsonDateDeserializer.class)
#Column(name = "END_DATE")
private Date endDate;}
And my ActivityDTO
#Getter
#Setter
public class ActivityDTO {
private Long id;
private Set<Attachment> attachments = new HashSet<>();
#Temporal(TemporalType.DATE)
#JsonSerialize(using = CustomJsonDateSerializer.class)
#JsonDeserialize(using = CustomJsonDateDeserializer.class)
private Date beginDate;
#Temporal(TemporalType.DATE)
#JsonSerialize(using = CustomJsonDateSerializer.class)
#JsonDeserialize(using = CustomJsonDateDeserializer.class)
private Date endDate;
And here is my ActivityController class;
public Activity save(ActivityDTO activityDTO, List<MultipartFile> fileList) throws Exception {
Activity activity = convertActivityDTOtoEntity(activityDTO);
activity.getAttachments().addAll(ObjectFactory.createAttachment(fileList, Activity.class));
return activityRepository.save(activity);
}
public Activity update(ActivityDTO activityDTO, List<MultipartFile> fileList) throws Exception {
Activity activity = convertActivityDTOtoEntity(activityDTO);
activity.getAttachments().addAll(ObjectFactory.createAttachment(fileList, Activity.class));
return activityRepository.save(activity);
}
private Activity convertActivityDTOtoEntity(ActivityDTO activityDTO) {
return modelMapper.map(activityDTO, Activity.class);
}
Also I have one more problem, I have just transformed my entity usage to DTO objects, until now service was reaching entity directly and while updating if I delete any attachment or add, there was no problem. After I transformed to DTO objects and used like above, there is a problem while updating;
detached entity passed to persist: com.thy.agencycrm.entity.Attachment
And here is my Attachment entity if you would like to see;
#Getter
#Setter
#Entity
public class Attachment implements Serializable {
#Id
#Column(name = "ID")
#GeneratedValue
#SequenceGenerator
private Long id;
#Column(name = "MIME_TYPE")
private String mimeType;
Please help me about this problem, I am searhing and trying to solve it for long times.
Thanks you in advance.

Answer 1

I think you just copy the fields into a new object in your converter right?
Default JPA only update the entity if it is in the persistance context and the two object are identical. If you have a detached object, create a new one with in the converter, it will be saved as new record. It does not matter if you set the ID, because the id is generated by the sequence, as you annotated on the entity class.
You can resolve this many ways. The easiest is to load the entity by id, and set the fields from the another object into this managed object.

Answer 2

Updated your Class ActivityController
public Activity save(ActivityDTO activityDTO, List<MultipartFile> fileList) throws Exception {
Activity activity = convertActivityDTOtoEntity(activityDTO);
activity.getAttachments().addAll(ObjectFactory.createAttachment(fileList, Activity.class));
return activityRepository.save(activity);
}
public Activity update(ActivityDTO activityDTO, List<MultipartFile> fileList) throws Exception {
Activity activity = activitiyRepository.findOne(activityDTO.getID());
// This will update the existing activity with activityDTO
modelMapper.map(activityDTO, activity);
activity.getAttachments().addAll(ObjectFactory.createAttachment(fileList, Activity.class));
return activityRepository.save(activity);
}
private Activity convertActivityDTOtoEntity(ActivityDTO activityDTO) {
return modelMapper.map(activityDTO, Activity.class);
}