I have two entities, a State and a Location. A State can have many locations.
This mapping should be pretty straightforward.
#Entity
#Table(name="Locations")
public class Location {
public Location() {};
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private int id;
#ManyToOne
#JoinColumn(name="StateCode")
private State state;
}
and the State class:
#Entity
#Table(name="States")
public class State {
private static final Logger log = LoggerFactory.getLogger(State.class);
public State() {
locations = new ArrayList<Location>();
};
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER, mappedBy="location")
private Collection<Location> locations;
#Id
#Column(name="StateCode", nullable=false, length=6)
private String stateCode;
public Collection<Location> getLocations() {
return locations;
}
public void setLocations( Collection<Location> locations ) {
this.locations = locations;
}
public String getStateCode() {
return stateCode;
}
public void setStateCode(String code) {
this.stateCode = code;
}
and yet I get this error:
AnnotationException mappedBy reference an unknown target entity property: net.rallaesystems.vibracheck.model.Location.location in net.rallaesystems.vibracheck.model.State.locations
I have followed the advice of changing the mapping to the 'state' field. With this code, though
#Repository
public interface StateRepository extends CrudRepository<State, String>{
List<State> findAll();
}
being called in a simple controller, the serialization of States goes into an infinite loop. Maybe there is a problem with the serialization library? I think it is Jackson.
You should update the #OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER, mappedBy="location") to #OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER, mappedBy="state"), this indicate the state is the owner
where the state is present in your Location class
#ManyToOne
#JoinColumn(name="StateCode")
private State state;
Yes, as somebody answered, you need use a valid property of the Location which is a foreign key on the location table (here its state property of location class, and statecode is foreign key in the location table).
Related
I have an issue, what I am close to solution or better said I come closer how to avoid the issue EntityExistsException: A different object with the same identifier value BUT without understanding what is really the problem. To keep code short and concentrated I did a small application to simulate the problem in my project.
First I have a CrudRepository what stays always the same:
public interface EntityARepository extends CrudRepository<EntityA, Long> {}
First I have to entities, one of them has a relation to the other:
#Entity
#EqualsAndHashCode(of={"name"})
#ToString(of={"name"})
#XmlRootElement
public class EntityA {
#Id
#GeneratedValue
#Setter
private Long id;
#Setter
#Column(nullable=false, unique=true)
private String name;
#Setter
#ManyToOne(fetch=EAGER, cascade={PERSIST, MERGE})
private EntityB entityB;
}
#ToString(of = { "name" })
#EqualsAndHashCode(of = { "name" })
#Entity
class EntityB {
#Id
// #GeneratedValue => produces issue!
#Setter
private Long id;
#Setter
#XmlAttribute
#Column(nullable=false, unique=true)
private String name;
}
Then I generate data and try to save them:
#Component
public class DatabaseInitializer implements InitializingBean {
#Autowired EntityARepository repository;
#Override
public void afterPropertiesSet() throws Exception {
final Set<EntityA> aEntities = createAEntities();
repository.save(aEntities);
}
private Set<EntityA> createAEntities() throws Exception {
Set<EntityA> aEntities = new HashSet<>();
aEntities.add(getFirstEntityA());
aEntities.add(getSecondEntityA());
return aEntities;
}
private EntityA getFirstEntityA(){
EntityA a = new EntityA();
// a.setId(1L);
a.setName("a-1");
a.setEntityB(getFirstEntityB());
return a;
}
private EntityA getSecondEntityA(){
EntityA a = new EntityA();
// a.setId(2L);
a.setName("a-2");
a.setEntityB(getFirstEntityB());
return a;
}
private EntityB getFirstEntityB() {
EntityB b = new EntityB();
b.setId(1l);
b.setName("b-1");
return b;
}
}
With this constallation I become a EntityExistsException:
Caused by: javax.persistence.EntityExistsException: A different object with the same identifier value was already associated with the session : [com.example.EntityB#1]
When firstEntityA gets saved, it also saves firstEntityB (because of cascade). So after that Session contains already entity of class EntityB with id 1.
When secondEntityA gets persisted, it also calls save on firstEntityB and then exception gets thrown.
The reason is that you can't call save on an object with id that is already present in the Session.
There are many ways to fix it. For example you can call merge instead of save.
repository.merge(aEntities);
Another way to fix this would to make both instances of EntityA have a referene to the same EntityB object:
private Set<EntityA> createAEntities() throws Exception {
Set<EntityA> aEntities = new HashSet<>();
EntityB entityB = getFirstEntityB();
aEntities.add(getFirstEntityA(entityB));
aEntities.add(getSecondEntityA(entityB));
return aEntities;
}
private EntityA getFirstEntityA(EntityB entityB){
EntityA a = new EntityA();
// a.setId(1L);
a.setName("a-1");
a.setEntityB(entityB);
return a;
}
private EntityA getSecondEntityA(EntityB entityB){
EntityA a = new EntityA();
// a.setId(2L);
a.setName("a-2");
a.setEntityB(entityB);
return a;
}
private EntityB getFirstEntityB() {
EntityB b = new EntityB();
b.setId(1l);
b.setName("b-1");
return b;
}
I've setup JPA auditing with Spring Data JPA AuditingEntityListener and AuditorAware bean. What I want is to be able to persist auditor details even on entities with predefined identifiers.
The problem is that when JPA entity with predefined id is being persisted and flushed it's auditor details cannot be persisted:
object references an unsaved transient instance - save the transient instance before flushing: me.auditing.dao.AuditorDetails
The interesting part is that when an entity with a generated id is saved - everything's fine. In both cases the entities are new. I could not pinpoint the problem digging through hibernate code so I've created a sample project to demonstrate this (test class me.auditing.dao.AuditedEntityIntegrationTest) It has both entities with predefined and generated identifiers and should be audited.
The entities are:
#Entity
public class AuditedEntityWithPredefinedId extends AuditableEntity {
#Id
private String id;
public String getId() {
return id;
}
public AuditedEntityWithPredefinedId setId(String id) {
this.id = id;
return this;
}
}
and:
#Entity
public class AuditedEntityWithGeneratedId extends AuditableEntity {
#Id
#GeneratedValue(generator = "uuid")
#GenericGenerator(name = "uuid", strategy = "uuid")
private String id;
public String getId() {
return id;
}
public AuditedEntityWithGeneratedId setId(String id) {
this.id = id;
return this;
}
}
where parent class is:
#MappedSuperclass
#EntityListeners(AuditingEntityListener.class)
public abstract class AuditableEntity implements Serializable {
private static final long serialVersionUID = -7541732975935355789L;
#ManyToOne(fetch = FetchType.EAGER, cascade = {CascadeType.ALL})
#CreatedBy
private AuditorDetails createdBy;
#CreatedDate
private LocalDateTime createdDate;
#ManyToOne(fetch = FetchType.EAGER, cascade = {CascadeType.ALL})
#LastModifiedBy
private AuditorDetails modifiedBy;
#LastModifiedDate
private LocalDateTime modifiedDate;
And the auditor getter implementation is:
#Override
public AuditorDetails getCurrentAuditor() {
return new AuditorDetails()
.setId(null)
.setUserId("someUserId")
.setDivisionId("someDivisionId");
}
Edit 2016-08-08: It seems that when a new entity with predefined id is saved, it gets two different instances of createdBy and modifiedBy AuditorDetails, which is quite logical if the entity wouldn't be actually new. So, a completely new entity with generated gets both AuditorDetails of same instance, and the one with manually set id doesn't. I tested it by saving auditor details in AuditorAware bean before returning it to AuditingHandler.
Ok, so for now the only solution I could find is to actually persist AuditorDetails before writing it to audited entities like so:
#Override
#Transactional
public AuditorDetails getCurrentAuditor() {
AuditorDetails details = new AuditorDetails()
.setId(null)
.setUserId("someUserId")
.setDivisionId("someDivisionId");
return auditorDetailsRepository.save(details);
}
It is not the most elegant solution, but it works for now.
I am making an application based on JPA/EclipseLink, I implemented a soft delete functionality using #AdditionalCriteria in the root class of the hierarchy of entities (all entities inherit from this).
My problem is that now, I need to create a special entity that contains multiple relationships with other entities; and I need recover all relationed entities, including soft deleted ones. It is possible disabled #AdditionalCriteria only in the relations of this special entity with EclipseLink? If not, what is the best option to do this? My code looks like the following:
////Example of my top entity class (all others inherit from this)
#AdditionalCriteria("this.deleted = false")
public abstract class TopHierarchyClass {
···
#Column(name = "deleted")
protected boolean deleted = false;
···
}
//Example of entity that needs recover all relationed entities including soft deleted
#Entity
#Table(name = "special_entities")
public class SpecialEntity extends EntityBase {
···
#JoinColumn(name = "iditem", referencedColumnName = "id")
#ManyToOne(fetch = FetchType.LAZY)
private Item item;
···
}
#Entity
#Table(name = "items")
public class Item extends EntityBase {
···
}
Thanks in advance
Create a new entity for the same table without the #AdditionalCriteria. This way you can retrieve all records from that table without applying the additional filter.
For example:
public interface Person {
Long getId();
void setId(Long id);
Date getDeletedAt();
void setDeletedAt(Date deletedAt);
}
#MappedSupperclass
public class PersonEntity implements Person {
#Id
private Long id;
private Date deletedAt;
public Long getId() { return id; }
public void setId(Long id) { this.id = id; }
public Date getDeletedAt() { return deletedAt; }
public void setDeletedAt(Date deletedAt) { this.deletedAt = deletedAt; }
}
#Entity
#Table(name = "people")
#AdditionalCriteria("this.deletedAt is null")
public class ActivePersonEntity extends PersonEntity {
}
#Entity
#Table(name = "people")
public class RawPersonEntity extends PersonEntity {
}
public class PeopleRepository {
#PersistenceContext
private EntityManager em;
public List<Person> all() {
return all(false);
}
public List<Person> all(boolean includeSoftDeleted) {
if (!includeSoftDeleted) {
return em.createQuery("select p from ActivePersonEntity p", ActivePersonEntity.class).getResultList();
} else {
return em.createQuery("select p from RawPersonEntity p", RawPersonEntity.class).getResultList();
}
}
}
Also, if your #AdditionalCriteria is in a super class, you may override it by declaring a new empty #AdditionalCriteria in a sub class:
You can define additional criteria on entities or mapped superclass.
When specified at the mapped superclass level, the additional criteria
definition applies to all inheriting entities, unless those entities
define their own additional criteria, in which case those defined for
the mapped superclass are ignored.
#AdditionalCriteria doc
I have have two classes that inherit from an abstract class and have a parent-children relation.
So I use annotation OneToMany and ManyToOne but the parent entity in child class is always null.
Can Someone help me please, I have spend several hours to googling and test many conf without success.
These are code from my classes :
public #Table(name="flowentity") #Entity abstract class FlowEntity {
final static Logger log = LoggerFactory.getLogger(FlowEntity.class);
//Globals informations concerning the flow state
private #Id #GeneratedValue(strategy = GenerationType.IDENTITY) Integer flowId = 0;
private String flowName;
private #OneToMany(fetch=FetchType.EAGER, cascade=CascadeType.ALL)
Set<PeopleEntity> actorSet = new HashSet<>();
//Global parameters for most of flows
//Organizational parameters
private #OneToOne(fetch=FetchType.EAGER, cascade=CascadeType.ALL)
#JoinColumn(name="organisationalEntity_Id")
OrganisationalEntity organisationalEntity;
...
public #Table(name="ams_newCPEntity") #Entity class NewMultiCPEntity extends FlowEntity {
private #OneToMany(targetEntity=NewCPEntity.class, fetch=FetchType.EAGER, cascade=CascadeType.ALL,mappedBy="parent")
Set<NewCPEntity> cpList = new HashSet<NewCPEntity>();
//Constructor
public NewMultiCPEntity(){
setFlowName(EnumFlow.N_CP_M.getFlowAcronym());
}
...
public #Table(name="ams_newCPEntity") #Entity class NewCPEntity extends FlowEntity {
final static Logger log = LoggerFactory.getLogger(NewCPEntity.class);
private boolean formNCPValidated;
private #ManyToOne #JoinColumn(name="parent_Id", nullable=false)
NewMultiCPEntity parent;
public NewCPEntity(){
log.debug("Instanciation of a new CP");
setFlowName(EnumFlow.N_CP.getFlowAcronym());
}
public #Override OrganisationalEntity getOrganisationalEntity(){
return parent.getOrganisationalEntity();
}
...
If I don't add the #JoinColumn annotation, JPA create an association table but is not able to retrieve the parent whereas the association can be done directly by requesting in database.
Thankyou very much to help.
Regards,
Thank you Chris for your comment, you are right, I forget to change the name of the table. I don't think it was the problem because the inheritance mapping is in one table flowentity with a DTYPE discriminator column.
Finally I resolve my problem by setting parent attributs when adding a new child like this :
public #Table #Entity class NewMultiCPEntity extends FlowEntity {
private #OneToMany(targetEntity=NewCPEntity.class, fetch=FetchType.EAGER, cascade=CascadeType.ALL)
List<NewCPEntity> cpList = new ArrayList<>();
//Constructor
public NewMultiCPEntity(){
setOrganisationalEntity(new OrganisationalEntity());
setFlowName(EnumFlow.N_CP_M.getFlowAcronym());
}
public List<NewCPEntity> getNCPList(){
if(cpList == null){
cpList = new ArrayList<>();
}
if(cpList.isEmpty()){
addCPEntity(new NewCPEntity());
}
return Collections.unmodifiableList(cpList);}
public boolean removeCPEntity(NewCPEntity entity){
return cpList.remove(entity);
}
public boolean addCPEntity(NewCPEntity entity){
entity.setParent(this);
entity.setOrganisationalEntity(this.getOrganisationalEntity());
return cpList.add(entity);
}
And I remove the override of getOrganizationalEntity in the child :
public #Table #Entity class NewCPEntity extends FlowEntity {
final static Logger log = LoggerFactory.getLogger(NewCPEntity.class);
private #ManyToOne(targetEntity=NewMultiCPEntity.class,cascade=CascadeType.ALL)
NewMultiCPEntity parent;
public NewCPEntity(){
log.debug("Instanciation of a new CP");
setFlowName(EnumFlow.N_CP.getFlowAcronym());
}
public NewMultiCPEntity getParent() {
return parent;
}
public void setParent(NewMultiCPEntity parent){
this.parent = parent;
}
Regards,
Here is a composite primary key for one of my entities.
public class GroupMembershipPK implements Serializable{
private static final long serialVersionUID = 7816433876820743311L;
private User user;
private Group group;
public GroupMembershipPK(){
}
public boolean equals(Object o){
if(o==null){
return false;
}
if(o instanceof GroupMembershipPK){
final GroupMembershipPK groupMembershipPK=(GroupMembershipPK)o;
return groupMembershipPK.group.getGroupName().equals(this.group.getGroupName()) &&
groupMembershipPK.user.getName().equals(this.user.getName());
}
return false;
}
public int hashCode(){
return super.hashCode();
}
}
Heres my entity(part of) using the above as a Composite Primary Key.
#Entity
#IdClass(GroupMembershipPK.class)
public class GroupMembership extends AbstractModelElementVersionOther{
private static final long serialVersionUID = 9188465566607060376L;
private String memType;
private Group group;
private User user;
public GroupMembership(){
super();
}
#Column(nullable=false)
public String getMemType(){
return this.memType;
}
public void setMemType(String memType){
this.memType=memType;
}
#Id
#ManyToOne
#JoinColumn(name="groupId")
public Group getGroup(){
return this.group;
}
public void setGroup(Group group){
this.group=group;
}
#Id
#ManyToOne
#JoinColumn(name="userId")
public User getUser(){
return this.user;
}
public void setUser(User user){
this.user=user;
}
#Override
public boolean equals(Object o) {
//
I am a little confused on what should be the equals method implementation for the above entity. How can I compare two composite primary keys?
Any comments on other parts of my code are welcome too.
It is not a good idea you store entities as primary key. There is some limitations when using query language and JPA 1.0 does not support. Besides it there is no need to use entities as primary key. Think about it.If you want, take a special look at the following question
A class that behaves like #Entity and #Embeddable
Answer one
Comment about answer one
You will see that using a entity as primary key is not necessary.
Instead of
public class GroupMembershipPK implements Serializable {
private User user;
private Group group;
}
Use
public class GroupMembershipPK implements Serializable {
private Integer userId;
private Integer groupId;
}
equals implementation is important because JPA compares two entities by using it (JPA checks whether an entity is in persistence context by using equals implementation). So you can implement according to
public boolean equals(Object o) {
if(o == null)
return false;
if(!(o instanceof GroupMembershipPK))
return false;
GroupMembershipPK other = (GroupMembershipPK) o;
if(!(getUserId().equals(other.getUserId()))
return false;
if(!(getGroupId().equals(other.getGroupId()))
return false;
return true;
}
Advice: it is a good idea you use property access instead of field access because, at some times, JPA implementation uses a proxy object because of performance issues. A proxy object makes use of property access because it allows JPA implementation hits the database when necessary.
How to save an object that uses a composite primary key ?
User user = new user();
Group group = new Group();
entityManager.save(user);
entityManager.save(group);
entityManager.flush();
UserGroup userGroup = new UserGroup();
userGroup.setId(new UserGroup.UserGroupId(user.getId(), group.getId()));
entityManager.save(userGroup);
Do you want to know how to implement UserGroup ?
public class UserGroup {
private UserGroupId id;
// You can create UserGroupId outside UserGroup class
// Feel free to choice your best approach
#Embeddable
public static class UserGroupId implements Serializable {
private Integer userId;
private Integer groupId;
// required no-arg constructor
public UserGroupId() {}
public UserGroupId(Integer userId, Integer groupId) {
this.userId = userId;
this.roupId = groupId;
}
// getter's and setter's
// equals and hashcode as shown above
}
#EmbeddedId
public UserGroupId getId() {
return this.id;
}
public setId(UserGroupId id) {
this.id = id;
}
}
Another approach to use composite primary key is IdClass. See IdClass
regards,
It was mentioned partially, anyway:
When implementing the equals method, you should use instanceof to allow comparing with subclasses. If Hibernate lazy loads a one to one or many to one relation, you will have a proxy for the class instead of the plain class. A proxy is a subclass. Comparing the class names would fail.
More technically, you should follow the Liskovs Substitution Principle and ignore symmetry.
The next pitfall is using something like name.equals(that.name) instead of name.equals(that.getName()). The first will fail, if that is a proxy.
http://www.laliluna.de/jpa-hibernate-guide/ch06s06.html