PersistentObjectException: detached entity passed to persist thrown by JPA and Hibernate
entity, hibernate, java, jpa, persist
Solution
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.
Problem
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?