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Thread safe spring data delete

I have two entities with one-to-one association. And some services that works with them in parallel. I need to delete one, but sometimes i have DataIntegrityViolationException, that as i understand means that i can't delete some entity while other has foreign key on it.
Here is my entities:
public class Foo{
#Id
#GeneratedValue
private Long id;
}
and:
public class Bar{
#Id
#GeneratedValue
private Long id;
#ManyToOne
private Foo foo;
}
Method that doesn't work (all repos extends from JpaRepository):
#Transactional
public void deleteFoo(Long fooId) {
barRepository.deleteAllByFooId(fooId);
fooRepository.deleteById(fooId);
}
And some method that works in parallel and breaks everything:
#Transactional
public void method(Long fooId) {
...
Foo foo = fooRepository.findById(fooId);
barRepository.save(new Bar(foo));
...
}
So i have ConstraintViolationException, as i understand because im trying to delete Foo but i have that new Bar(foo) in method that wasn't deleted by barRepository.deleteAllByFooId(fooId) in deleteFoo .
I need some approach like "delete method should wait until all current transactions finishes and then run only one transaction".
Can't use KeyLockManager because real structure of project already enough complicated and if i use it it should be same lock in many classes.

The problem is that you try to delete entity that being used in transaction. To close transaction you could use repository's save() method.
Also you should look at cascades and orphan removal. Use like this:
In Bar entity:
#ManyToOne(cascade = CascadeType.REMOVE, orphanRemoval = true)
private Foo foo;
And delete like so:
barRepository.save(bar);
or so:

How to add existing value in many to many relationship spring boot [duplicate]

I have a JPA-persisted object model that contains a many-to-one relationship: an Account has many Transactions. A Transaction has one Account.
Here's a snippet of the code:
#Entity
public class Transaction {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#ManyToOne(cascade = {CascadeType.ALL},fetch= FetchType.EAGER)
private Account fromAccount;
....
#Entity
public class Account {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#OneToMany(cascade = {CascadeType.ALL},fetch= FetchType.EAGER, mappedBy = "fromAccount")
private Set<Transaction> transactions;
I am able to create an Account object, add transactions to it, and persist the Account object correctly. But, when I create a transaction, using an existing already persisted Account, and persisting the the Transaction, I get an exception:
Caused by: org.hibernate.PersistentObjectException: detached entity passed to persist: com.paulsanwald.Account
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:141)
So, I am able to persist an Account that contains transactions, but not a Transaction that has an Account. I thought this was because the Account might not be attached, but this code still gives me the same exception:
if (account.getId()!=null) {
account = entityManager.merge(account);
}
Transaction transaction = new Transaction(account,"other stuff");
// the below fails with a "detached entity" message. why?
entityManager.persist(transaction);
How can I correctly save a Transaction, associated with an already persisted Account object?

The solution is simple, just use the CascadeType.MERGE instead of CascadeType.PERSIST or CascadeType.ALL.
I have had the same problem and CascadeType.MERGE has worked for me.
I hope you are sorted.

This is a typical bidirectional consistency problem. It is well discussed in this link as well as this link.
As per the articles in the previous 2 links you need to fix your setters in both sides of the bidirectional relationship. An example setter for the One side is in this link.
An example setter for the Many side is in this link.
After you correct your setters you want to declare the Entity access type to be "Property". Best practice to declare "Property" access type is to move ALL the annotations from the member properties to the corresponding getters. A big word of caution is not to mix "Field" and "Property" access types within the entity class otherwise the behavior is undefined by the JSR-317 specifications.

Remove cascading from the child entity Transaction, it should be just:
#Entity class Transaction {
#ManyToOne // no cascading here!
private Account account;
}
(FetchType.EAGER can be removed as well as it's the default for #ManyToOne)
That's all!
Why? By saying "cascade ALL" on the child entity Transaction you require that every DB operation gets propagated to the parent entity Account. If you then do persist(transaction), persist(account) will be invoked as well.
But only transient (new) entities may be passed to persist (Transaction in this case). The detached (or other non-transient state) ones may not (Account in this case, as it's already in DB).
Therefore you get the exception "detached entity passed to persist". The Account entity is meant! Not the Transaction you call persist on.
You generally don't want to propagate from child to parent. Unfortunately there are many code examples in books (even in good ones) and through the net, which do exactly that. I don't know, why... Perhaps sometimes simply copied over and over without much thinking...
Guess what happens if you call remove(transaction) still having "cascade ALL" in that #ManyToOne? The account (btw, with all other transactions!) will be deleted from the DB as well. But that wasn't your intention, was it?

Don't pass id(pk) to persist method or try save() method instead of persist().

Removing child association cascading
So, you need to remove the #CascadeType.ALL from the #ManyToOne association. Child entities should not cascade to parent associations. Only parent entities should cascade to child entities.
#ManyToOne(fetch= FetchType.LAZY)
Notice that I set the fetch attribute to FetchType.LAZY because eager fetching is very bad for performance.
Setting both sides of the association
Whenever you have a bidirectional association, you need to synchronize both sides using addChild and removeChild methods in the parent entity:
public void addTransaction(Transaction transaction) {
transcations.add(transaction);
transaction.setAccount(this);
}
public void removeTransaction(Transaction transaction) {
transcations.remove(transaction);
transaction.setAccount(null);
}

Using merge is risky and tricky, so it's a dirty workaround in your case. You need to remember at least that when you pass an entity object to merge, it stops being attached to the transaction and instead a new, now-attached entity is returned. This means that if anyone has the old entity object still in their possession, changes to it are silently ignored and thrown away on commit.
You are not showing the complete code here, so I cannot double-check your transaction pattern. One way to get to a situation like this is if you don't have a transaction active when executing the merge and persist. In that case persistence provider is expected to open a new transaction for every JPA operation you perform and immediately commit and close it before the call returns. If this is the case, the merge would be run in a first transaction and then after the merge method returns, the transaction is completed and closed and the returned entity is now detached. The persist below it would then open a second transaction, and trying to refer to an entity that is detached, giving an exception. Always wrap your code inside a transaction unless you know very well what you are doing.
Using container-managed transaction it would look something like this. Do note: this assumes the method is inside a session bean and called via Local or Remote interface.
#TransactionAttribute(TransactionAttributeType.REQUIRED)
public void storeAccount(Account account) {
...
if (account.getId()!=null) {
account = entityManager.merge(account);
}
Transaction transaction = new Transaction(account,"other stuff");
entityManager.persist(account);
}

Probably in this case you obtained your account object using the merge logic, and persist is used to persist new objects and it will complain if the hierarchy is having an already persisted object. You should use saveOrUpdate in such cases, instead of persist.

My Spring Data JPA-based answer: I simply added a #Transactional annotation to my outer method.
Why it works
The child entity was immediately becoming detached because there was no active Hibernate Session context. Providing a Spring (Data JPA) transaction ensures a Hibernate Session is present.
Reference:
https://vladmihalcea.com/a-beginners-guide-to-jpa-hibernate-entity-state-transitions/

An old question, but came across the same issue recently . Sharing my experience here.
Entity
#Data
#Entity
#Table(name = "COURSE")
public class Course {
#Id
#GeneratedValue
private Long id;
}
Saving the entity (JUnit)
Course course = new Course(10L, "testcourse", "DummyCourse");
testEntityManager.persist(course);
Fix
Course course = new Course(null, "testcourse", "DummyCourse");
testEntityManager.persist(course);
Conclusion : If the entity class has #GeneratedValue for primary key (id), then ensure that you are not passing a value for the primary key (id)

If nothing helps and you are still getting this exception, review your equals() methods - and don't include child collection in it. Especially if you have deep structure of embedded collections (e.g. A contains Bs, B contains Cs, etc.).
In example of Account -> Transactions:
public class Account {
private Long id;
private String accountName;
private Set<Transaction> transactions;
#Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof Account))
return false;
Account other = (Account) obj;
return Objects.equals(this.id, other.id)
&& Objects.equals(this.accountName, other.accountName)
&& Objects.equals(this.transactions, other.transactions); // <--- REMOVE THIS!
}
}
In above example remove transactions from equals() checks. This is because hibernate will imply that you are not trying to update old object, but you pass a new object to persist, whenever you change element on the child collection.
Of course this solutions will not fit all applications and you should carefully design what you want to include in the equals and hashCode methods.

In your entity definition, you're not specifying the #JoinColumn for the Account joined to a Transaction. You'll want something like this:
#Entity
public class Transaction {
#ManyToOne(cascade = {CascadeType.ALL},fetch= FetchType.EAGER)
#JoinColumn(name = "accountId", referencedColumnName = "id")
private Account fromAccount;
}
EDIT: Well, I guess that would be useful if you were using the #Table annotation on your class. Heh. :)

Even if your annotations are declared correctly to properly manage the one-to-many relationship you may still encounter this precise exception. When adding a new child object, Transaction, to an attached data model you'll need to manage the primary key value - unless you're not supposed to. If you supply a primary key value for a child entity declared as follows before calling persist(T), you'll encounter this exception.
#Entity
public class Transaction {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
....
In this case, the annotations are declaring that the database will manage the generation of the entity's primary key values upon insertion. Providing one yourself (such as through the Id's setter) causes this exception.
Alternatively, but effectively the same, this annotation declaration results in the same exception:
#Entity
public class Transaction {
#Id
#org.hibernate.annotations.GenericGenerator(name="system-uuid", strategy="uuid")
#GeneratedValue(generator="system-uuid")
private Long id;
....
So, don't set the id value in your application code when it's already being managed.

Here is my fix.
Below is my Entity. Mark that the id is annotated with #GeneratedValue(strategy = GenerationType.AUTO), which means that the id would be generated by the Hibernate. Don't set it when entity object is created. As that will be auto generated by the Hibernate.
Mind you if the entity id field is not marked with #GeneratedValue then not assigning the id a value manually is also a crime, which will be greeted with IdentifierGenerationException: ids for this class must be manually assigned before calling save()
#Entity
#Data
#NamedQuery(name = "SimpleObject.findAll", query="Select s FROM SimpleObject s")
public class SimpleObject {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#Column
private String key;
#Column
private String value;
}
And here is my main class.
public class SimpleObjectMain {
public static void main(String[] args) {
System.out.println("Hello Hello From SimpleObjectMain");
SimpleObject simpleObject = new SimpleObject();
simpleObject.setId(420L); // Not right, when id is a generated value then no need to set this.
simpleObject.setKey("Friend");
simpleObject.setValue("Bani");
EntityManager entityManager = EntityManagerUtil.getEntityManager();
entityManager.getTransaction().begin();
entityManager.persist(simpleObject);
entityManager.getTransaction().commit();
List<SimpleObject> simpleObjectList = entityManager.createNamedQuery("SimpleObject.findAll").getResultList();
for(SimpleObject simple : simpleObjectList){
System.out.println(simple);
}
entityManager.close();
}
}
When I tried saving that, it was throwing that
PersistentObjectException: detached entity passed to persist.
All I needed to fix was remove that id setting line for the simpleObject in the main method.

Maybe It is OpenJPA's bug, When rollback it reset the #Version field, but the pcVersionInit keep true. I have a AbstraceEntity which declared the #Version field. I can workaround it by reset the pcVersionInit field. But It is not a good idea. I think it not work when have cascade persist entity.
private static Field PC_VERSION_INIT = null;
static {
try {
PC_VERSION_INIT = AbstractEntity.class.getDeclaredField("pcVersionInit");
PC_VERSION_INIT.setAccessible(true);
} catch (NoSuchFieldException | SecurityException e) {
}
}
public T call(final EntityManager em) {
if (PC_VERSION_INIT != null && isDetached(entity)) {
try {
PC_VERSION_INIT.set(entity, false);
} catch (IllegalArgumentException | IllegalAccessException e) {
}
}
em.persist(entity);
return entity;
}
/**
* #param entity
* #param detached
* #return
*/
private boolean isDetached(final Object entity) {
if (entity instanceof PersistenceCapable) {
PersistenceCapable pc = (PersistenceCapable) entity;
if (pc.pcIsDetached() == Boolean.TRUE) {
return true;
}
}
return false;
}

You need to set Transaction for every Account.
foreach(Account account : accounts){
account.setTransaction(transactionObj);
}
Or it colud be enough (if appropriate) to set ids to null on many side.
// list of existing accounts
List<Account> accounts = new ArrayList<>(transactionObj.getAccounts());
foreach(Account account : accounts){
account.setId(null);
}
transactionObj.setAccounts(accounts);
// just persist transactionObj using EntityManager merge() method.

cascadeType.MERGE,fetch= FetchType.LAZY

Resolved by saving dependent object before the next.
This was happened to me because I was not setting Id (which was not auto generated). and trying to save with relation #ManytoOne

#OneToMany(mappedBy = "xxxx", cascade={CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REMOVE})
worked for me.

In my case I was committing transaction when persist method was used.
On changing persist to save method , it got resolved.

If above solutions not work just one time comment the getter and setter methods of entity class and do not set the value of id.(Primary key)
Then this will work.

Another reason I have encountered this issue is having Entities that aren't versioned by Hibernate in a transaction.
Add a #Version annotation to all mapped entities
#Entity
public class Customer {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private UUID id;
#Version
private Integer version;
#OneToMany(cascade = CascadeType.ALL)
#JoinColumn(name = "orders")
private CustomerOrders orders;
}
#Entity
public class CustomerOrders {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private UUID id;
#Version
private Integer version;
private BigDecimal value;
}

This error comes from the JPA Lifecycle.
To solve, no need to use specific decorator. Just join the entity using merge like that :
entityManager.merge(transaction);
And don't forget to correctly set up your getter and setter so your both side are sync.

So I stumbled across this Question and Answers because I got the same Error but a very basic object with just Strings and Integers.
But in my case I was trying to set a Value to a Field which was annotated with #Id.
So if you are using #Id it seems that you can't create a new Object on a Class and set an Id by yourself and persist it to Database. You should then leave the Id blank. I wasn't aware and maybe this helps anyone else.

The problem here is lack of control.
When we use the CrudRepository/JPARepository save method we loose the transactional control.
To overcome this issue we have Transaction Management
I prefer the #Transactional mechanism
imports
import javax.transaction.Transactional;
Entire Source Code:
package com.oracle.dto;
import lombok.*;
import javax.persistence.*;
import java.util.Date;
import java.util.List;
#Entity
#Data
#ToString(exclude = {"employee"})
#EqualsAndHashCode(exclude = {"employee"})
public class Project {
#Id
#GeneratedValue(strategy = GenerationType.AUTO,generator = "ps")
#SequenceGenerator(name = "ps",sequenceName = "project_seq",initialValue = 1000,allocationSize = 1)
#Setter(AccessLevel.NONE)
#Column(name = "project_id",updatable = false,nullable = false)
private Integer pId;
#Column(name="project_name",nullable = false,updatable = true)
private String projectName;
#Column(name="team_size",nullable = true,updatable = true)
private Integer teamSize;
#Column(name="start_date")
private Date startDate;
#ManyToMany(cascade = CascadeType.ALL)
#JoinTable(name="projectemp_join_table",
joinColumns = {#JoinColumn(name = "project_id")},
inverseJoinColumns = {#JoinColumn(name="emp_id")}
)
private List<Employee> employees;
}
package com.oracle.dto;
import lombok.*;
import javax.persistence.*;
import java.util.List;
#Entity
#Data
#EqualsAndHashCode(exclude = {"projects"})
#ToString(exclude = {"projects"})
public class Employee {
#Id
#GeneratedValue(strategy = GenerationType.AUTO,generator = "es")
#SequenceGenerator(name = "es",sequenceName = "emp_seq",allocationSize = 1,initialValue = 2000)
#Setter(AccessLevel.NONE)
#Column(name = "emp_id",nullable = false,updatable = false)
private Integer eId;
#Column(name="fist_name")
private String firstName;
#Column(name="last_name")
private String lastName;
#ManyToMany(mappedBy = "employees")
private List<Project> projects;
}
package com.oracle.repo;
import com.oracle.dto.Employee;
import org.springframework.data.jpa.repository.JpaRepository;
public interface EmployeeRepo extends JpaRepository<Employee,Integer> {
}
package com.oracle.repo;
import com.oracle.dto.Project;
import org.springframework.data.jpa.repository.JpaRepository;
public interface ProjectRepo extends JpaRepository<Project,Integer> {
}
package com.oracle.services;
import com.oracle.dto.Employee;
import com.oracle.dto.Project;
import com.oracle.repo.ProjectRepo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import javax.transaction.Transactional;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;
#Component
public class DBServices {
#Autowired
private ProjectRepo repo;
#Transactional
public void performActivity(){
Project p1 = new Project();
p1.setProjectName("Bank 2");
p1.setTeamSize(20);
p1.setStartDate(new Date(2020, 12, 22));
Project p2 = new Project();
p2.setProjectName("Bank 1");
p2.setTeamSize(21);
p2.setStartDate(new Date(2020, 12, 22));
Project p3 = new Project();
p3.setProjectName("Customs");
p3.setTeamSize(11);
p3.setStartDate(new Date(2010, 11, 20));
Employee e1 = new Employee();
e1.setFirstName("Pratik");
e1.setLastName("Gaurav");
Employee e2 = new Employee();
e2.setFirstName("Ankita");
e2.setLastName("Noopur");
Employee e3 = new Employee();
e3.setFirstName("Rudra");
e3.setLastName("Narayan");
List<Employee> empList1 = new LinkedList<Employee>();
empList1.add(e2);
empList1.add(e3);
List<Employee> empList2 = new LinkedList<Employee>();
empList2.add(e1);
empList2.add(e2);
List<Project> pl1=new LinkedList<Project>();
pl1.add(p1);
pl1.add(p2);
List<Project> pl2=new LinkedList<Project>();
pl2.add(p2);pl2.add(p3);
p1.setEmployees(empList1);
p2.setEmployees(empList2);
e1.setProjects(pl1);
e2.setProjects(pl2);
repo.save(p1);
repo.save(p2);
repo.save(p3);
}
}

hibernate collections with inheritance

My case is a form, with categories, questions, answers... A form has different categories, each of one have different questions and this questions one or more possible answers.
In my imnplementation of java, I hava an object called TreeObject that implements all relationship between elements (and other common properties as creation date...). This object has a list of childs and a parent to follow the hierarchy of the form. Then, Category, Form and other elements extends this class and add some extra functionality.
The database will be a table with all common data (tree object) and childs and parent relationship, and some other tables (forms, categories, ...) with specific data for each one. For this I use InheritanceType.JOINED
The code of the Tree Object class (UPDATED to include #kostja comments):
#Entity
#Table(name = "TREE_OBJECTS")
#Inheritance(strategy = InheritanceType.JOINED)
public abstract class TreeObject implements ITreeObject {
#Id
#GeneratedValue(strategy = GenerationType.TABLE)
#Column(name = "ID", unique = true, nullable = false)
private Long id;
#OneToMany(cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
#JoinTable(name = "CHILDRENS_RELATIONSHIP")
private List<TreeObject> children;
#ManyToOne(fetch = FetchType.EAGER)
private TreeObject parent;
//More parameters, getters and setters.
}
For example the Form class is:
#Entity
#Table(name = "FORMS")
public class Form extends TreeObject {
private String name;
//setters, getters and other stuff.
}
And the DAO has this method (I am using generics for simplifying the code but the code can be read):
public T makePersistent(T entity) {
setCreationInfo(entity);
setUpdateInfo(entity);
Session session = getSessionFactory().getCurrentSession();
session.beginTransaction();
try {
session.saveOrUpdate(entity);
session.flush();
session.getTransaction().commit();
return entity;
} catch (RuntimeException e) {
session.getTransaction().rollback();
throw e;
}
}
Category, Questions and other elements are very similar to the Form class. The I skip them.
The problem is that the children list is not persisted correctly. For example the next test fails because getChildren().size() is 0 and not 1 (but other forms values are retrieved correctly, only the child list is empty):
#Test
public void storeFormWithCategory() throws NotValidChildException {
Form form = new Form();
form.setName("Test Form");
Category category = new Category();
form.addChild(category);
formDao.makePersistent(form);
Form retrievedForm = formDao.read(form.getId());
Assert.assertEquals(retrievedForm.getId(), form.getId());
Assert.assertEquals(retrievedForm.getChildren().size(), 1);
}
If I move the code of the child list into the Form class, it works correctly and the test is passed. But the list inside the parent class is not working. I cannot understand why, the only difference is the use of the inheritance.

The problem was solved removing the Interface. I have read that hibernate cannot work with intefaces, and this is the reason why children parameter is not implemented with interfaces. Removing the interface implementation and changing some setters and getters methods (as getChildren) to use TreeObject solve the issue. I have thinked that not using the interface with the DAO was enought to solve this issue. But seems that the getters and setters of the object also must not use the inteface.
Probably, when I have copied to Form object I haven't use the interface as a quick copy paste, and this is the reason why has worked correctly in this case.

CascadeType doesn't work in in-memory database

I have a webapp with database where two Entities have many-to-many relationship but I implemented join table manually. When one of the entities gets deleted it deletes all entries in the join table and updates the other entity so all works perfectly fine, but now I'm supposed to write a test for this feature. For tests I am using in-memory database and that's really the only difference, the same methods with the same annotations (and cascade types) are called but I keep getting:
org.hibernate.exception.ConstraintViolationException: integrity constraint violation: foreign key no action; FKC17477FD8940DF2B table ENTITY1_ENTITY2
I didn't paste any code as I don't believe there is anything wrong with it since it's working. I don't ask to fix this for me, I just need to know what is likely to cause this kind of behavior because I've just ran out of ideas and I don't know what else to search for... Thanks
EDIT: here's some code:
#Entity
#Table(name = "interviewer")
public class Interviewer implements Identifiable {
#OneToMany(fetch = FetchType.EAGER)
#JoinColumn(name = "interviewer_id")
private Collection<InterviewerTechnology> technologies;
}
#Entity
#Table(name = "technology")
public class Technology implements Identifiable {
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
#JoinColumn(name = "technology_id")
private Collection<InterviewerTechnology> technologies;
}
#Entity
#Table(name = "interviewer_technology")
public class InterviewerTechnology implements Identifiable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#ManyToOne(cascade = CascadeType.MERGE, fetch = FetchType.LAZY)
private Interviewer interviewer;
#ManyToOne(cascade = CascadeType.MERGE, fetch = FetchType.EAGER)
private Technology technology;
}
#Component
public class TechnologyDao extends AbstractEntityDao<Technology> {
public void remove(Integer id) {
Technology technology = find(id);
em.remove(technology);
}
}
This code does exactly what I want it to do, it just seems like database used for tests does not see CascadeType parameters that do all the job here

I have found the problem and it was #Transactional annotation. All my test DAOs were extending generic test DAO which was annotated with #Transactional and I blindly annotated every single DAO with it again. The problem here is that some operations need to be performed as single transactions (may need flush() after being executed) so that data is available for other operations straight away. Consider following example:
#Transactional
public abstract class AbstractEntityDao<E> {
#PersistenceContext(unitName = "some-persistence")
protected EntityManager em;
public E create(E e) {
em.persist(e);
return e;
}
(...)
}
which means that every method in this class is a transaction. Now if we annotate another class that extends this class with #Transactional every method will be another transaction, which means if we delete several things in one method it should take several transactions (they all need flush() method to be called in order to execute cascade) but instead they will run as one transaction (unless we specify Propagation). Let this be a lesson for everyone (especially me) to think carefully about which operations need separate transactions and which can be executed as one.

Unique constraint violation with ordered Hibernate list

I have the following entities and get an exception if I try to remove a Task from the TaskList via removeTask method.
#Entity
public class TaskList extends GenericModel {
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER)
#OrderColumn(name="position", nullable=false)
public List<Task> tasks = new ArrayList<>();
// ...
public void removeTask(Task task) {
tasks.remove(task);
}
}
#Entity
public class Task extends Model {
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER)
#JoinColumn(name="task_id")
private List<Reservation> reservations = new ArrayList<>();
#ManyToOne
public TaskList taskList;
// ...
}
#Entity
public class Reservation extends GenericModel {
#Id
private String id = Token.generate(8);
#ManyToOne
private Task task;
// ...
}
The exception is:
"CONSTRAINT_INDEX_F ON PUBLIC.TASKLIST_TASK(TASKS_ID)"
Unique index or primary key violation: "CONSTRAINT_INDEX_F ON PUBLIC.TASKLIST_TASK(TASKS_ID)"; SQL statement:
update TaskList_Task set tasks_id=? where TaskList_id=? and position=? [23001-149]
I'm using JPA 2 with Hibernate 3.6.1. Is something wrong with my mapping or is it a Hibernate bug?
UPDATE
It seems to be a Hibernate problem. Something with the order of delete and update statements. The following hack solved the problem (partly):
#Entity
public class TaskList extends GenericModel {
// ....
public void removeTask(Task task) {
tasks.remove(task);
tasks = new ArrayList<>(tasks); // only for Hibernate
task.taskList = null;
}
}
Hibernate - clearing a collection with all-delete-orphan and then adding to it causes ConstraintViolationException lead my in the right direction.
But orphanRemoval=true doesn't work with my workaround. It leads to the next exception: "A collection with cascade="all-delete-orphan" was no longer referenced by the owning entity instance". So the problem is not really solved.

Your bidirectional association is mapped twice: once in TaskList, and once in Task. The mapping annotations in TaskList should be
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER, mappedBy="task")
#OrderColumn(name="position", nullable=false)
public List<Task> tasks = new ArrayList<>();
Without the mappedBy attribute, Hibernate considers that you have two separate associations (and I doubt that's what you want), rather than a bidirectional one.
Moreover, when you modify a bidirectional association, both sides of the association should be modified. So the removeTask method should be
public void removeTask(Task task) {
tasks.remove(task);
task.setTaskList(null);
}
That's particularly important, because the owning side of the association is Task (because that's where ther is no mappedBy attribute). So this is the side that Hibernate inspects to know that the association must be removed.