Let´s assume these two entities:
#Entity
public class MyEntity {
#Id private String id;
#OneToMany(mappedBy = "myEntity", cascade = ALL) private Set<MyEntityPredecessor> predecessors;
}
#Entity
public class MyEntityPredecessor{
#Id private String id;
#ManyToOne(name = "entityID", nullable = false) private MyEntity myEntity;
#ManyToOne(name = "entityPre", nullable = false) private MyEntity predecessor;
}
When I try to call a delete with Spring Boot Data (JPA) with a MyEntity Instance, it will work some times (I see the select and then the delete statements in correct order), but sometimes it will try to run an update on the second entity trying to set the "entityPre" Field to null (even thoug it is set to nullable=falsE), causing the DB to send an error (null not allowed!! from DB constraint).
Strangely, this will happen at "random" calls to the delete...
I just call "myEntityRepository.getOne(id)", and then myEntityRepository.delete() with the result... There is no data difference in the DB between calls, the data structure has no null values when calling the delete method, so that should not be the reason.
Why is JPA sometimes trying to call updates on the Predecessor Table, and sometimes directly deleting the values? Am I missing something?
Add a similar ManyToOne annotated set to MyEntity which refers to the other non-nullable property, like:
#OneToMany(mappedBy = "predecessor", cascade = ALL) private Set<MyEntityPredecessor> other;
some explanation:
The issue doesn't happen randomly, but happen when you try to delete an entity which is linked to one (or more) MyEntityPredecessor via the predecessor property (which is mapped to the entityPre field)
Only the other field (entityID) is mapped back to the MyEntity object, so the deletion-cascade only happens via by that field.
Related
I have a DB (Postgres) table with a unique constraint for one column. I have a test marked with #Transactional annotation, that updates that unique column value to a not unique value. I expect that the update operation should fail, but it executes successfully. Moreover, when I get updated object from the database (inside the same transaction), the column value is updated there.
The simplified version of JPA entity:
#Entity
#Table(name = "entities")
public class Entity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
// The unique column
#Column(name = "name", unique = true)
#NotNull
private String name;
...
}
The simplified version for the test:
#Test
#Transactional
public void test() {
Entity firstEntity = new Entity();
firstEntity.setName("First Entity Name");
// This just calls corresponding JPA repository .save method
entityService.create(firstEntity);
Entity secondEntity = new Entity();
secondEntity.setName("Second Entity Name");
entityService.create(secondEntity);
// Update name to a not unique value
secondEntity.setName(firstEntity.getName);
// This calls corresponding JPA repository .save method.
// It also catches DataIntegrityViolationException and throws
// a more user friendly exception instead
entityService.update(secondEntity);
}
This code works as I expect, if #Transactional annotation is removed or transaction is committed. I also tried to call EntityManager.flush(), as advised here, but this code throws ConstraintViolationException after resulting data is flushed, so I can't test that my entityService.update method works correctly and throws proper exception.
Please also note that if I try to create a new entry with not unique data in transactional test (not update), then test works as expected -
DataIntegrityViolationException is thrown when not unique entity is created.
Could somebody clarify if it is possible to make update scenario work as expected keeping test transactional so I don't need to care about data clean up?
Here are my entities:
#Entity
public class Actor {
private List<Film> films;
#ManyToMany
#JoinTable(name="film_actor",
joinColumns =#JoinColumn(name="actor_id"),
inverseJoinColumns = #JoinColumn(name="film_id"))
public List<Film> getFilms(){
return films;
}
//... more in here
Moving on:
#Entity
public class Film {
private List actors;
#ManyToMany
#JoinTable(name="film_actor",
joinColumns =#JoinColumn(name="film_id"),
inverseJoinColumns = #JoinColumn(name="actor_id"))
public List<Actor> getActors(){
return actors;
}
//... more in here
And the join table:
#javax.persistence.IdClass(com.tugay.sakkillaa.model.FilmActorPK.class)
#javax.persistence.Table(name = "film_actor", schema = "", catalog = "sakila")
#Entity
public class FilmActor {
private short actorId;
private short filmId;
private Timestamp lastUpdate;
So my problem is:
When I remove a Film from an Actor and merge that Actor, and check the database, I see that everything is fine. Say the actor id is 5 and the film id is 3, I see that these id 's are removed from film_actor table..
The problem is, in my JSF project, altough my beans are request scoped and they are supposed to be fetching the new information, for the Film part, they do not. They still bring me Actor with id = 3 for Film with id = 5. Here is a sample code:
#RequestScoped
#Named
public class FilmTableBackingBean {
#Inject
FilmDao filmDao;
List<Film> allFilms;
public List<Film> getAllFilms(){
if(allFilms == null || allFilms.isEmpty()){
allFilms = filmDao.getAll();
}
return allFilms;
}
}
So as you can see this is a request scoped bean. And everytime I access this bean, allFilms is initially is null. So new data is fetched from the database. However, this fetched data does not match with the data in the database. It still brings the Actor.
So I am guessing this is something like a cache issue.
Any help?
Edit: Only after I restart the Server, the fetched information by JPA is correct.
Edit: This does not help either:
#Entity
public class Film {
private short filmId;
#ManyToMany(mappedBy = "films", fetch = FetchType.EAGER)
public List<Actor> getActors(){
return actors;
}
The mapping is wrong.
The join table is mapped twice: once as the join table of the many-to-many association, and once as an entity. It's one or the other, but not both.
And the many-to-many is wrong as well. One side MUST be the inverse side and use the mappedBy attribute (and thus not define a join table, which is already defined at the other, owning side of the association). See example 7.24, and its preceeding text, in the Hibernate documentation (which also applies to other JPA implementations)
Side note: why use a short for an ID? A Long would be a wiser choice.
JB Nizet is correct, but you also need to maintain both sides of relationships as there is caching in JPA. The EntityManager itself caches managed entities, so make sure your JSF project is closing and re obtaining EntityManagers, clearing them if they are long lived or refreshing entities that might be stale. Providers like EclipseLink also have a second level cache http://wiki.eclipse.org/EclipseLink/Examples/JPA/Caching
I'm trying to save an object called Stat using EclipseLink. If the id exists in the db, update that object. If not, create a new object. Here is my object:
#Entity
public class Stat {
#Column
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
public long id;
#JoinColumn
#ManyToOne
public User user;
#Column
public boolean accepted;
#Column
public boolean finished;
public Stat() {
}
}
And here is my method for adding/updating the object.
public long addReplaceStat(Stat stat) {
em.getTransaction().begin();
Stat oldStat = em.find(Stat.class, stat.id);
if (oldStat == null)
em.persist(stat);
else
em.merge(stat);
em.getTransaction().commit();
em.getTransaction().begin();
Stat newStat = em.find(Stat.class, stat.id);
if (newStat != null)
em.refresh(newStat);
em.getTransaction().commit();
return stat.id;
}
My problem is that I get exception at em.refresh() saying "The attribute [id] of class [User] is mapped to a primary key column in the database. Updates are not allowed." And I don't understand why. Shouldn't refresh just update the values of my managed object without problem?
What is the best idiom to do what I want (add or update)?
The JPA spec says:
The semantics of the merge operation applied to an entity X are as
follows:
If X is a detached entity, the state of X is copied onto a pre-existing managed entity instance X' of the same identity or a new
managed copy X' of X is created.
If X is a new entity instance, a new managed entity instance X' is created and the state of X is copied into the new managed entity
instance X'.
[...]
So to add if not existing or update is it exists, you just need to do:
Stat attachedStat = em.merge(stat);
Regarding your problem with refresh, I don't know why it happens. But why are you refreshing an entity that you just loaded from the database? There is nothing to refresh.
the question and problem is pretty simple, though annoying and I am looking for a global solution, because it's application-wide problem for us.
The code below is really not interesting but I post it for clarification!
We use PostgreSQL database with JPA 2.0 and we generated all the facades and entities, of course we did some editing but not much really.
The problem is that every entity contains a Collection of its children, which however (for us only?) is NOT updated after creation a children element.
The objects are written to database, you can select them easily, but what we really would like to see is the refreshed collection of children in parent object.
Why is this happening? If we (manually) refresh the entity of parent em.refresh(parent) it does the trick but it would mean for us a lot of work in Facades I guess. But maybe there is no other way?
Thanks for support!
/* EDIT */
I guess it has to be some annotation problem or cache or something, but I've already tried
#OneToMany(mappedBy = "idquestion", orphanRemoval=true, fetch= FetchType.EAGER)
and
#Cacheable(false)
didn't work properly.
/* EDIT */
Some sample code for understanding.
Database level:
CREATE TABLE Question (
idQuestion SERIAL,
questionContent VARCHAR,
CONSTRAINT Question_idQuestion_PK PRIMARY KEY (idQuestion)
);
CREATE TABLE Answer (
idAnswer SERIAL,
answerContent VARCHAR,
idQuestion INTEGER,
CONSTRAINT Answer_idAnswer_PK PRIMARY KEY (idAnswer),
CONSTRAINT Answer_idQuestion_FK FOREIGN KEY (idQuestion) REFERENCES Question(idQuestion)
);
Than we have generated some Entities in Netbeans 7.1, all of them look similar to:
#Entity
#Table(name = "question", catalog = "jobfairdb", schema = "public")
#XmlRootElement
#NamedQueries({ BLAH BLAH BLAH...})
public class Question implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Basic(optional = false)
#NotNull
#GeneratedValue(strategy= GenerationType.IDENTITY)
#Column(name = "idquestion", nullable = false)
private Integer idquestion;
#Size(max = 2147483647)
#Column(name = "questioncontent", length = 2147483647)
private String questioncontent;
#OneToMany(mappedBy = "idquestion", orphanRemoval=true)
private Collection<Answer> answerCollection;
Getters... setters...
We use (again) generated facades for them, all implementing AbstractFacade like:
public abstract class CCAbstractFacade<T> {
private Class<T> entityClass;
public CCAbstractFacade(Class<T> entityClass) {
this.entityClass = entityClass;
}
protected abstract EntityManager getEntityManager();
public void create(T entity) {
getEntityManager().persist(entity);
}
The father entity is updated automatically if you use container managed transactions and you fetch the collection after the transaction is complete. Otherwise, you have to update yourself the collection.
This article explains in detail this behaviour: JPA implementation patterns: Bidirectional associations
EDIT:
The simplest way to use Container Managed Transactions is to have transaction-type="JTA" in persistence.xml and use Container-Managed Entity Managers.
You seem to be setting the ManyToOne side, but not adding to the OneToMany, you have to do both.
In JPA, and in Java in general you must update both sides of a bi-directional relationship, otherwise the state of your objects will not be in sync. Not doing so, would be wrong in any Java code, not just JPA.
There is no magic in JPA that will do this for you. EclipseLink does have a magic option for this that you could set through a customizer (mapping.setRelationshipPartnerAttributeName()), but it is not recommended, fixing your code to be correct is the best solution.
See,
http://en.wikibooks.org/wiki/Java_Persistence/Relationships#Object_corruption.2C_one_side_of_the_relationship_is_not_updated_after_updating_the_other_side
I have a very basic relationship between two objects:
#Entity
public class A {
#ManyToOne(optional = false)
#JoinColumn(name="B_ID", insertable=false, updatable=true)
private StatusOfA sa;
getter+setter
}
#Entity
public class StatusOfA {
#Id
private long id;
#Column
private String status;
getter+setter
}
There's only a limited set of StatusOfA in DB.
I perform an update on A in a transaction:
#TransactionalAttribute
public void updateStatusOfA(long id) {
A a = aDao.getAById(123);
if(a != null) {
a.getStatusOfA().getId(); //just to ensure that the object is loaded from DB
StatusOfA anotherStatusOfA = statusOfADao.getStatusOfAById(456);
a.setStatusOfA(aontherStatusOfA);
aDao.saveOrPersistA(a);
}
}
The saveOrPersistA method is here merging 'a'.
I expect Eclipselink to perform only an update on 'a' to update the StatusOfA but it's executing a new insert on StatusOfA table. Oracle is then complaining due to a unique contraint violation (the StatusOfA that Eclipselink tries to persist already exists...).
There is no Cascading here so the problem is not there and Hibernate (in JPA2) is behaving as excepted.
In the same project, I already made some more complex relationships and I'm really surprised to see that the relation here in not working.
Thanks in advance for your help.
What does, statusOfADao.getStatusOfAById() do?
Does it use the same persistence context (same transaction and EntityManager)?
You need to use the same EntityManager, as you should not mix objects from different persistence contexts.
What does saveOrPersistA do exactly? The merge() call should resolve everything correctly, but if you have really messed up objects, it may be difficult to merge everything as you expect.
Are you merging just A, or its status as well? Try also setting the status to the merged result of the status.
Assumptions: #Id#GeneratedValue(strategy = GenerationType.IDENTITY)
Let's consider the following implementations of statusOfADao.getStatusOfAById(456) :
1. returns "proxy" object with just id set:
return new StatusOfA(456);
2. returns entity in new transaction:
EntityManager em = emf.createEntityManager();em.getTransaction().begin();
StatusOfA o = em.find(StatusOfA.class,456);//em.getReference(StatusOfA.class,456);
em.getTransaction().commit();
return o;
3. returns detached entity:
StatusOfA o = em.find(StatusOfA.class,456);//em.getReference(StatusOfA.class,456);
em.detached(o);
return o;
4. returns deserialized-serialized entity:
return ObjectCloner.deepCopy(em.find(StatusOfA.class,456));
5. returns attached entity:
return em.find(StatusOfA.class,456);
Conclusions:
Eclipselink handles only implementation N5 as "expected".
Hibernate handles all five implementations as "expected".
No analisys of what behaviour is jpa spec compliant