jpa: update relationship for a new parent-entity - jpa

Question

i have two entities Price<-1----1->PriceDetail mapped as OneToOne.
how can i handle different scenarios for this relation. so i have cases where i always want a new price and a new pricedetail,
but i also would be able to create a new price only and update the pricedetail (with data from a previous price-entity).
my current solution is to remove the pricedetail-entity, how can it be done with updating the pricedetail-entity?
#Entity
class Price {
#OneToOne(cascade=CascadeType.ALL,mappedBy = "price")
private PriceDetail priceDetail;
}
#Entity
class PriceDetail {
#OneToOne
private Price price;
}
save-method:
EntityManage em = getEntityManager();
for (Price price : getAllPrices()){
Price oldPrice = Price.getById(price.getId());
if (!oldPrice.equals(price)){ //if we have price-changes
if (PriceCatalog.entryExists(oldPrice)){ //if the current-price is in a catalog
//current solution: remove entry from PriceDetail, but i want to update PriceDetail-Entity, pointing
//to the newly created price
em.remove(oldPrice.getPriceDetail());
em.commitTransaction();
oldPrice.setActive(false); //referenced price in PriceCatalog is now inactive
//sets id null, so that a new price-entity is created
price.setId(null);
price.setActive(true);
em.persist(price); //also inserts a new price-detail
}else {
em.merge(price);
}
}
}
em.commitTransaction();
because of CascadeType.ALL-Annotation in Price-Entity, JPA tries to insert a new PriceDetail-Entity.
approach 1:
price.getPriceDetail().setId(oldPrice.getPriceDetail().getId());
-> Error: insert into pricedetail violates unique-constraint: Key already exists
approach 2:
//ommit cascade
#OneToOne(mappedBy = "price")
protected PriceDetail priceDetail;
then approach 1 works, but creating a complete new price results in:
During synchronization a new object was found through a relationship that was not marked cascade PERSIST

Answer 1

approach 2 is not an option in you case, this is the correct mapping to do a bidirectional one-to-one association:
//you must do this to handle the bidirectional association
#OneToOne(mappedBy = "price")
protected PriceDetail priceDetail;
Now the problem is :price is a new entity then the entityManager will call persit operation on price.getpriceDetail() because cascade persist is triggered automatically (not cascade-merge) to avoid this strange behaviour you can do the following.
EntityManage em = getEntityManager();
for (Price price : getAllPrices()){
Price oldPrice = Price.getById(price.getId());
if (!oldPrice.equals(price)){ //if we have price-changes
if (PriceCatalog.entryExists(oldPrice)){ //if the current-price is in a catalog
//current solution: remove entry from PriceDetail, but i want to update PriceDetail-Entity, pointing
//to the newly created price
//em.remove(oldPrice.getPriceDetail());
//em.commitTransaction();
oldPrice.setActive(false); //referenced price in PriceCatalog is now inactive
PriceDetail priceDetailold = price.getPriceDetail();
price.setPriceDetail(null);
priceDetailold.setPrice(null);
//sets id null, so that a new price-entity is created
price.setId(null);
price.setActive(true);
em.persist(price); //inserts a new price
price.setPriceDetail(priceDetailold);
em.merge(price);// attach the pricedetail to the price
}else {
em.merge(price);
}
}
}
em.commitTransaction();