JPA persisting objects without calling persist

I have an entity class Document and another one called Space. The relation:

@ManyToOne(fetch = FetchType.EAGER, cascade = {Ca开发者_C百科scadeType.PERSIST,
        CascadeType.MERGE, CascadeType.REFRESH}, optional = true)
@ForeignKey(name = "FK_TO_SPACE__DOCUMENT")
@IndexedEmbedded(prefix = DocumentDefaultFields.SPACE_TO_PREFIX)
private Space toSpace;

Well, i do query the db and take some docs into a LinkedList.

This list is binded to a dataTable from where i can do some update operations like:

<a:commandLink value="move" action="#{moveDocsOperation.moveDocumentToNewSpace(entity)}" reRender="confim,origTable,newTable"/>

and the method:

public void moveDocumentToNewSpace(final Document document) {
    log.info("~~move document #0 from space #1 to space #2", document.getDocumentId(), origSpace.getPath(), newSpace.getPath());
    document.setToSpace(newSpace);
    origSpaceDocuments.remove(document);
    newSpaceDocuments.add(document);
    entityAuditer.auditBean(document, Crud.UPDATE);
}

I do not understand why, when setting the toSpace of the document entity, the update is also done in DB without actually doing PERSIST....

do you know WHY?

When you load an object via the hibernate session, it is managed by that session. When you make changes, at flush time the changes in the object are synchronized with the database.

So calling persist() is not needed to persist data modifications. (Related: http://techblog.bozho.net/?p=227)

One way you can get round this and make changes to the entity without persisting to the database is by removing from session:

org.hibernate.Session session = (Session) em.getDelegate();
session.evict(yrEnity);