hibernate - delete from many-to-many - java

I have the following two POJOs:
#Entity(name = "project")
#Table(name = "project")
public class Project {
#Column(name = "identifier")
#Id
#GeneratedValue
private Integer identifier;
#ManyToMany(cascade = CascadeType.ALL)
private Set<Member> members = new HashSet<Member>();
// --- constructors ---
public Project() {
}
// --- getters ---
public Integer getIdentifier() {
return identifier;
}
public Set<Member> getMembers() {
return members;
}
}
and
#Entity(name = "member")
#Table(name = "member")
public class Member {
#Column(name = "identifier")
#Id
#GeneratedValue
private Integer identifier;
#Column(name = "name", columnDefinition = "text")
private String name;
#ManyToMany(mappedBy = "members")
private Set<Project> projects = new HashSet<Project>();
// --- constructors ---
public Member() {
}
// --- getters ---
public Integer getIdentifier() {
return identifier;
}
public String getName() {
return name;
}
public Set<Project> getProjects() {
return projects;
}
}
What is common practise do delete from a many-to-many relation? The following code works perfectly, but it generates a lot of overhead. First, there are some queries:
1 query to get the projects, triggered by member.getProjects()
N queries to get all members of the each project, triggered by project.getMembers()
Second, the complete data set of the project (query 1) and member (query 2) is fetched, and not only the identifier.
final Member member = ...;
for (final Project project : member.getProjects()) {
project.getMembers().remove(member);
}
db.delete(member);
Is it possible to do this more efficient without being forced to write ad-hoc queries?

Take a look here:
How to remove entity with ManyToMany relationship in JPA (and corresponding join table rows)?
Additionally you have the option to use jpql statements to delete data:
http://docs.oracle.com/html/E24396_01/ejb3_overview_query.html#ejb3_overview_query_delete
But I think the first link is what you are looking for.

Related

Scan all fields in dtos and find missing and extra fields by their Entities

I want to create a unit test that will use reflection to find all missing fields in dto that implement BaseDto by their persistence entities. This is what I did.
#Slf4j
public class EntityAuditDtoTest {
#Test
public void find_MissingAndExtraFieldsThatUsedInAuditDtosByEntity_ReturnMissingAndExtraFields() throws ClassNotFoundException {
// Arrange
ClassPathScanningCandidateComponentProvider scanner = new ClassPathScanningCandidateComponentProvider(false);
scanner.addIncludeFilter(new AnnotationTypeFilter(AuditEntityType.class));
// Find all classes annotated with #AuditEntityType in the package com.example.dto
Set<BeanDefinition> auditDtoBeans = scanner.findCandidateComponents("com.example.dto");
// Act
for (BeanDefinition auditDtoBean : auditDtoBeans) {
Class<?> auditDtoClass = Class.forName(auditDtoBean.getBeanClassName());
// Make sure the DTO class implements BaseAuditDto
if (!BaseAuditDto.class.isAssignableFrom(auditDtoClass)) {
continue;
}
Class<?> entityClass = getEntityClassForDto(auditDtoClass);
Field[] dtoFields = auditDtoClass.getDeclaredFields();
Field[] entityFields = entityClass.getDeclaredFields();
List<String> missingFields = Arrays.stream(entityFields).map(Field::getName)
.filter(field -> Arrays.stream(dtoFields).noneMatch(f -> f.getName().equals(field))).toList();
if (!missingFields.isEmpty()) {
log.error("Missing fields in DTO class: {} \nfor entity class: {} : {}", auditDtoClass.getName(),
entityClass.getName(), missingFields);
}
List<String> extraFields = Arrays.stream(dtoFields).map(Field::getName)
.filter(field -> Arrays.stream(entityFields).noneMatch(f -> f.getName().equals(field))).toList();
if (!extraFields.isEmpty()) {
log.error("Extra fields in DTO class: {} \nfor entity class: {} : {}", auditDtoClass.getName(),
entityClass.getName(), extraFields);
}
}
}
}
But the problem is that the dto may have a field that is in the entity class, but the test will think that this is a missing field.
For example:
Dto class: ContractAudit has customerId field (customerId). And ContractEntity has public CustomerEntity customer.
This is the same fields. But of course for test they are different. I don't understand how to ignore them. I also don't want to hardcode filter that skip all endings with 'id' prefix.
#Data
#AuditEntityType("Contract")
public class ContractAudit implements BaseAuditDto {
private Long id;
private String ref;
private String status;
private Long customerId;
}
#Entity
#Table(name = "contract")
#Getter
#Setter
#ToString
#AllArgsConstructor
#NoArgsConstructor
#Builder
public class ContractEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
#ToString.Include
private Long id;
#Column(name = "ref", updatable = true)
#ToString.Include
private String ref;
#Column(name = "status")
#ToString.Include
#Enumerated(value = EnumType.STRING)
private ContractStatusEnum status;
#ManyToOne
#JoinColumn(name = "customer_id")
public CustomerEntity customer;
#Column(name = "deleted")
#ToString.Include
private boolean deleted;
#OneToMany(fetch = FetchType.LAZY)
#JoinColumn(name = "contract_id")
private List<ContractDocumentEntity> documents;
}
Output:
Missing fields in DTO class: ContractAudit for entity class: ContractEntity : [customer, deleted, documents]
Extra fields in DTO class: ContractAudit for entity class: ContractEntity : [customerId]
I want to have missing fields: [deleted, documents]
If you have any other ideas on how to do this, I'd love to hear it. I am not asking for implementation. Suggestions only)
Lol. I found solution for my case.
My previous approach was incorrect. Because it's impossible to find 'missing' and 'extra' fields by name correctly for every case. I decided to use:
assertThat(entityClass.getDeclaredFields()).hasSameSizeAs(auditDtoClass.getDeclaredFields());
So this code is checking if the entityClass and the DtoClass have the same number of fields (properties) declared. If not it fail test and print all fields from each classes. If anyone has better ideas I'll be happy to hear.

update #OneToMany relationship (Spring Boot, Spring Data)

I have a OneToMany relationship (two tables bi-directional).
When I save the doctor's specialties, it does work, but when I remove any specialty and update the doctor, it doesn't.
Doctor
#Entity
#Table(name = "doctors")
public class Doctor implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer doctorId;
#Column(length = 20)
private String doctorName;
#Column(length = 9)
private String doctorPhoneNo;
#Column(length = 30)
private String doctorEmailAddress;
private String doctorProfileImage;
#Enumerated(EnumType.STRING)
private Status status;
#Column(length = 6)
private String doctorCmp;
#OneToMany(mappedBy = "doctor", cascade = CascadeType.ALL)
// #JsonIgnore
private Set<DoctorSpecialties> doctorSpecialties;
public Doctor() {
this.doctorSpecialties = new HashSet<>();
}
public Doctor(Integer id){
this();
this.doctorId = id;
}
// getters y setters
}
Specialty
#Entity
#Table(name = "specialties")
public class Specialty implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer specialtyId;
private String specialtyName;
#OneToMany(mappedBy = "specialty")
#JsonIgnore
private Set<DoctorSpecialties> doctorSpecialties;
public Specialty() {
}
public Specialty(Integer id) {
this.specialtyId = id;
}
// getters and setters
}
DoctorSpecialties
#Entity
#Table(name = "doctor_specialties")
public class DoctorSpecialties implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "doctor_id")
private Doctor doctor;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "specialty_id")
private Specialty specialty;
#OneToMany
#JoinColumn(name = "doctor_specialties_id")
private Set<Appointment> appointments;
#OneToMany
#JoinColumn(name = "doctor_specialties_id")
private Set<DoctorSchedule> schedules;
public DoctorSpecialties(){
}
public DoctorSpecialties(Specialty specialty, Doctor doctor){
this.specialty = specialty;
this.doctor = doctor;
}
getters / setters
}
Controller
#PostMapping(value = "/saveSpecialties/{id}")
public String saveDoctorSpecialties(#RequestParam(required = false) String[] specialtiesId,
#PathVariable Integer id, RedirectAttributes message) {
if (id != null && id > 0) {
Doctor doctor = doctorService.findOne(id);
if (doctor != null) {
// It does not work
doctor.getDoctorSpecialties().forEach(ds -> doctorSpecialtiesService.delete(ds.getId()));
doctor.getDoctorSpecialties().clear();
if (specialtiesId != null) {
for (String specialtyId : specialtiesId) {
DoctorSpecialties ds = new DoctorSpecialties();
ds.setSpecialty(new Specialty(Integer.parseInt(specialtyId)));
ds.setDoctor(doctor);
doctor.getDoctorSpecialties()
.add(ds);
}
}
doctorService.update(doctor);
message.addFlashAttribute("success", "Specialties successfully saved.");
return "redirect:/doctors/profile/{id}/specialties";
}
}
// specialtiesId = new String[]{};
message.addFlashAttribute("error", "Doctor doesn't exists");
return "redirect:/doctors/list";
}
console:
2021-10-30 21:19:13.330 DEBUG 44504 --- [nio-8080-exec-7] org.hibernate.SQL : select doctor0_.doctor_id as doctor_i1_3_0_, doctor0_.doctor_cmp as doctor_c2_3_0_, doctor0_.doctor_email_address as doctor_e3_3_0_, doctor0_.doctor_name as doctor_n4_3_0_, doctor0_.doctor_phone_no as doctor_p5_3_0_, doctor0_.doctor_profile_image as doctor_p6_3_0_, doctor0_.status as status7_3_0_ from doctors doctor0_ where doctor0_.doctor_id=?
2021-10-30 21:19:13.339 DEBUG 44504 --- [nio-8080-exec-7] org.hibernate.SQL : select doctorspec0_.doctor_id as doctor_i2_2_0_, doctorspec0_.id as id1_2_0_, doctorspec0_.id as id1_2_1_, doctorspec0_.doctor_id as doctor_i2_2_1_, doctorspec0_.specialty_id as specialt3_2_1_ from doctor_specialties doctorspec0_ where doctorspec0_.doctor_id=?
2021-10-30 21:19:13.401 DEBUG 44504 --- [nio-8080-exec-8] org.hibernate.SQL : select doctor0_.doctor_id as doctor_i1_3_0_, doctor0_.doctor_cmp as doctor_c2_3_0_, doctor0_.doctor_email_address as doctor_e3_3_0_, doctor0_.doctor_name as doctor_n4_3_0_, doctor0_.doctor_phone_no as doctor_p5_3_0_, doctor0_.doctor_profile_image as doctor_p6_3_0_, doctor0_.status as status7_3_0_ from doctors doctor0_ where doctor0_.doctor_id=?
2021-10-30 21:19:13.404 DEBUG 44504 --- [nio-8080-exec-8] org.hibernate.SQL : select specialty0_.specialty_id as specialt1_7_0_, doctorspec1_.id as id1_2_1_, doctor2_.doctor_id as doctor_i1_3_2_, specialty0_.specialty_name as specialt2_7_0_, doctorspec1_.doctor_id as doctor_i2_2_1_, doctorspec1_.specialty_id as specialt3_2_1_, doctorspec1_.specialty_id as specialt3_2_0__, doctorspec1_.id as id1_2_0__, doctor2_.doctor_cmp as doctor_c2_3_2_, doctor2_.doctor_email_address as doctor_e3_3_2_, doctor2_.doctor_name as doctor_n4_3_2_, doctor2_.doctor_phone_no as doctor_p5_3_2_, doctor2_.doctor_profile_image as doctor_p6_3_2_, doctor2_.status as status7_3_2_ from specialties specialty0_ inner join doctor_specialties doctorspec1_ on specialty0_.specialty_id=doctorspec1_.specialty_id inner join doctors doctor2_ on doctorspec1_.doctor_id=doctor2_.doctor_id where doctor2_.doctor_id=?
2021-10-30 21:19:13.565 DEBUG 44504 --- [nio-8080-exec-4] org.hibernate.SQL : select specialty0_.specialty_id as specialt1_7_0_, doctorspec1_.id as id1_2_1_, doctor2_.doctor_id as doctor_i1_3_2_, specialty0_.specialty_name as specialt2_7_0_, doctorspec1_.doctor_id as doctor_i2_2_1_, doctorspec1_.specialty_id as specialt3_2_1_, doctorspec1_.specialty_id as specialt3_2_0__, doctorspec1_.id as id1_2_0__, doctor2_.doctor_cmp as doctor_c2_3_2_, doctor2_.doctor_email_address as doctor_e3_3_2_, doctor2_.doctor_name as doctor_n4_3_2_, doctor2_.doctor_phone_no as doctor_p5_3_2_, doctor2_.doctor_profile_image as doctor_p6_3_2_, doctor2_.status as status7_3_2_ from specialties specialty0_ inner join doctor_specialties doctorspec1_ on specialty0_.specialty_id=doctorspec1_.specialty_id inner join doctors doctor2_ on doctorspec1_.doctor_id=doctor2_.doctor_id where doctor2_.doctor_id=?
There is no delete statement...
------------------------
EDIT 1
------------------------
Doctor find = doctorRepository.findById(1).get();
DoctorSpecialties ds1 = new DoctorSpecialties();
ds1.setSpecialty(specialtyRepository.findById(1).get());
ds1.setDoctor(find);
DoctorSpecialties ds2 = new DoctorSpecialties();
ds2.setSpecialty(specialtyRepository.findById(2).get());
ds2.setDoctor(find);
find.getDoctorSpecialties().add(ds1);
find.getDoctorSpecialties().add(ds2);
doctorRepository.save(find);
I have done some tests and I can not understand completely. I did and it only saves once when actually I am adding two objects.
insert into doctor_specialties (id, doctor_id, specialty_id) values (null, ?, ?)
------------------------
EDIT 2
------------------------
DoctorSpecialties (Modify the constructor)
#Entity
#Table(name = "doctor_specialties")
public class DoctorSpecialties implements Serializable {
public DoctorSpecialties(Integer specialtyId, Doctor doctor) {
this.specialty = new Specialty(specialtyId);
this.doctor = doctor;
}
}
Controller
#PostMapping(value = "/saveSpecialties/{id}")
public String saveDoctorSpecialties(#RequestParam(required = false) String[] specialtiesId,
#PathVariable Integer id, RedirectAttributes message) {
if (id != null && id > 0) {
doctorService.saveDelete(id);
Doctor doctor = doctorService.findOne(id);
if (specialtiesId != null && specialtiesId.length > 0) {
for(String idSpecialty : specialtiesId){
doctorSpecialtiesService.save(new DoctorSpecialties(Integer.parseInt(idSpecialty), doctor));
}
}
message.addFlashAttribute("success", "Specialties successfully saved.");
return "redirect:/doctors/profile/{id}/specialties";
}
message.addFlashAttribute("error", "Doctor doesn't exists");
return "redirect:/doctors/list";
}
Service
#Override
#Transactional
public void saveDelete(Integer doctorId) {
Doctor doctor = this.doctorRepository
.findById(doctorId).get();
doctor.getDoctorSpecialties().clear();
}
Console:
select doctor0_.doctor_id as doctor_i1_3_0_, doctor0_.doctor_cmp as doctor_c2_3_0_, doctor0_.doctor_email_address as doctor_e3_3_0_, doctor0_.doctor_name as doctor_n4_3_0_, doctor0_.doctor_phone_no as doctor_p5_3_0_, doctor0_.doctor_profile_image as doctor_p6_3_0_, doctor0_.status as status7_3_0_ from doctors doctor0_ where doctor0_.doctor_id=?
select doctorspec0_.doctor_id as doctor_i2_2_0_, doctorspec0_.id as id1_2_0_, doctorspec0_.id as id1_2_1_, doctorspec0_.doctor_id as doctor_i2_2_1_, doctorspec0_.specialty_id as specialt3_2_1_ from doctor_specialties doctorspec0_ where doctorspec0_.doctor_id=?
update appointments set doctor_specialties_id=null where
doctor_specialties_id=?
update doctor_schedules set
doctor_specialties_id=null where doctor_specialties_id=?
delete from doctor_specialties where id=?
For the one-many relationship in a transaction, once you get the parent (Doctor) and loop over its children (DoctorSpecialties) [In other words, once you load entire the parent and its children into Persistent state], you won't be able to delete your DoctorSpecialties directly by its repository.
You could try something like the below example to see it:
#Transactional
public void removeLine(Long doctorId, Long specId) {
Doctor doctor = this.doctorRepository // (1)
.findById(doctorId)
.orElseThrow(IllegalArgumentException::new);
this.doctorSpecialtiesRepository.deleteById(specId); // (2)
}
At (1), we load doctor into the persistent state. So here, if fetch = FetchType.EAGER, this means that it will load doctor and its all doctorSpecialties into the persistent state and this cause (2) won't give you any effect.
Otherwise, if fetch = FetchType.LAZY, it only load doctor into the persistent state, and at (2) it will be deleted successfully.
Your case was similar, although fetch = FetchType.LAZY, but you looped over the children by using forEach and that loads doctorSpecialties into the persistent state. That's why you cannot delete them.
Suggestion: Using orphanRemoval = true in your parent entity
#OneToMany(mappedBy = "doctor", cascade = CascadeType.ALL, orphanRemoval = true)
private Set<DoctorSpecialties> dss;
and just simply clear its children in your method (In #Transactional method)
doctor.getDoctorSpecialties().clear();
Whichever side has mappedBy is owning side.
This means something like: "modifications on this side of the relation
are already Mapped By the other side of the relation
, so no need to track it here separately in an extra
table."
Check this url for more information What is the "owning side" in an ORM mapping?

How to depict joins with #Query annotation in Spring JPA Repository method

I am using Spring-Boot with JPA and a MySQL backend. Now I got quite confused about the repositories Spring-Boot provides. I know these are quite powerful (and seem to be quite useful since they can shorten your code a lot). Still, I do not understand how to represent Joins within them, since the result-set should be a combination of specified attributes in the select of a few Entities.
Now let's assume we have three tables Book, Author, AuthorOfBook, where the last one is simply connecting Book and Author by a combined Primary key. I guess we had the following Java-Classes:
Entity Book:
#Entity
#Table(name="BOOK")
public class Book {
#Id #GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "ID")
private int id;
#Column(name = "TITLE")
private String title;
}
Entity Author
#Entity
#Table(name="AUTHOR")
public class Author {
#Id #GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "ID")
private int id;
#Column(name = "LASTNAME")
private String lastname;
#Column(name = "FIRSTNAME")
private String firstname;
//Let's assume some getters and setters and a constructor
}
Entity AuthorOfBook:
#Entity
#Table(name="BOOK")
public class Book {
#EmbeddedId
private AuthorOfBookId pk;
}
An Embedded ID
#Embeddable
public class AuthorOfBookId implements Serializable {
private int authorId;
private int bookId;
}
Repository
#Repository
public interface AuthorOfBookRepository extends JpaRepository<,AuthorOfBookId> {
}
Now how would I represent that query:
SELECT b.name, a.firstname, a.lastname from AuthorOfBook ab inner join Book b on b.id = ab.book_id inner join Author a on a.id = ab.author_id where a.lastname = :lastname;
in my repository? I know the signature would need to be like
#Query([the query string from above])
public (...) findAuthorAndBookByAuthorLastname(#Param("lastname") String lastname);
but I cannot make out what Type the return would be like. What is that method returning? (simply AuthorOfBook would not work I guess)
You don't want AuthorOfBook as a separate Entity. Book should have a field of type Author as a #ManyToOne relationship. That way, given any Book, you can find the author's details.
If you want to handle audits fields you can do something like this:
Audit class
#Embeddable
public class Audit {
#Column(name = "created_on")
private Timestamp createdOn;
#Column(name = "updated_on")
private Timestamp updatedOn;
#Column(name = "is_deleted")
private Boolean isDeleted;
//getters and setters
}
AuditListener to update automatically audits fields
public class AuditListener {
private Long loggedUser = 1001L;
/**
* Method to set the fields createdOn, and isDeleted when an entity is persisted
* #param auditable
*/
#PrePersist
public void setCreatedOn(Auditable auditable) {
Audit audit = auditable.getAudit();
if (audit == null) {
audit = new Audit();
auditable.setAudit(audit);
}
audit.setIsDeleted(Boolean.FALSE);
audit.setCreatedOn(Timestamp.from(Instant.now()));
}
/**
* Method to set the fields updatedOn and updatedBy when an entity is updated
* #param auditable
*/
#PreUpdate
public void setUpdatedOn(Auditable auditable) {
Audit audit = auditable.getAudit();
audit.setUpdatedOn(Timestamp.from(Instant.now()));
}
}
And add this to the entities
#EntityListeners(AuditListener.class)
public class Book implements Auditable {
#Embedded
private Audit audit;

Hibernate mapping collection inside container entity

I have the following class structure:
public class Container {
private Set<Child> childs = new HashSet<>();
}
public class Child {
String name;
String value;
String param;
}
Because of Container class is going to be single in application (just wrapper on collections that may be updated), I would like to store it in single table, e.g."childs" with columns
id | name | value | param
Is it possible to make such mapping in order to use Container when fetch or
store it through hb session with corresponding updates to childs collection:
getSession().saveOrUpdate(container)
And if so, what mapping should be in that case?
UPD: I was going to have 2 classes mapped to single table
After some research I ended up with such solution:
#Entity
#Table(name = "childs")
public class Container {
#Id
//optional your id strategy
#GeneratedValue(strategy = GenerationType.AUTO, generator = "xyz")
Long id;
#ElementCollection(fetch = FetchType.EAGER)
#CollectionTable(name="childs", joinColumns=#JoinColumn(name="id"))
private Set<Child> childs = new HashSet<>();
}
#Embeddable
public class Child {
String name;
String value;
String param;
}
table structure - childs(id, name, value, param)
im not sure about the getSession().saveOrUpdate(container) , but the mapping for you problem should look something like this.
#Entity
public class Container {
#ManyToOne
private Set<Child> childs = new HashSet<>();
}
#Entity
public class Child {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
Long id;
String name;
String value;
String param;
}

How do I setup annotations for JOINED inheritance with composite PK in hibernate?

I am new to hibernate and having a tough time trying to wrap my head around setting up Joined inheritance with composite Primary Key. With my current setup, I get a:
JDBCException: could not insert: LandHolidayPackage
I am essentially looking for two things:
Are the inheritance annotations in place ?
Is the composite PK setup properly ?
DB Design:
Reference
Here are my classes and the annotations involved:
#Entity
#Table(name = "HOLIDAYPACKAGE")
public final class HolidayPackage {
private Integer idPackage;
private String name;
private Set<HolidayPackageVariant> holidayPackageVariants = new HashSet<HolidayPackageVariant>(0);
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "IDHOLIDAYPACKAGE", nullable = false)
public Integer getIdPackage() {
return idPackage;
}
#OneToMany(fetch=FetchType.LAZY, cascade={CascadeType.ALL}, mappedBy = "holidayPackage")
public Set<HolidayPackageVariant> getHolidayPackageVariants() {
return holidayPackageVariants;
}
// ommitted other part of the code
}
#Entity
#Inheritance(strategy=InheritanceType.JOINED)
#Table(name="HOLIDAYPACKAGEVARIANT")
public abstract class HolidayPackageVariant {
private Integer idHolidayPackageVariant;
private HolidayPackage holidayPackage;
private String typeHolidayPackage;
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(name="IDHOLIDAYPACKAGEVARIANT", nullable=false)
public Integer getIdHolidayPackageVariant() {
return idHolidayPackageVariant;
}
#ManyToOne(fetch=FetchType.LAZY, cascade={CascadeType.ALL})
#JoinColumn(name="IDHOLIDAYPACKAGE", nullable=false)
public HolidayPackage getHolidayPackage() {
return holidayPackage;
}
#Column(name="TYPEHOLIDAYPACKAGE", nullable=true)
public String getTypeHolidayPackage() {
return typeHolidayPackage;
}
// ommitted setters, equals hashCode
}
#Entity
#Table(name="LANDHOLIDAYPACKAGEVARIANT")
public final class LandHolidayPackageVariant extends HolidayPackageVariant{
private static final String LAND = "LAND";
protected LandHolidayPackageVariant() {}
public LandHolidayPackageVariant(HolidayPackage holidayPackage) {
super(holidayPackage, LAND);
}
}
#Entity
#Table(name="FLIGHTHOLIDAYPACKAGEVARIANT")
public final class FlightHolidayPackageVariant extends HolidayPackageVariant{
private static final String FLIGHT = "FLIGHT";
private Destination originCity;
protected FlightHolidayPackageVariant(){}
public FlightHolidayPackageVariant(HolidayPackage holidayPackage,
Destination originCity) {
super(holidayPackage, FLIGHT);
setOriginCity(originCity);
}
#ManyToOne(fetch=FetchType.LAZY, cascade={CascadeType.ALL})
#JoinColumn(name="IDDESTINATION", nullable=false)
public Destination getOriginCity() {
return originCity;
}
// ommited other setters etc functions
}
You annotated the properties in stead of the fields. JPA by default tries to access the fields. If you want JPA to use the fields you have to annotate the class with #AccessType(AccessType.Field).

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