When persisting or removing entity, all your references are by default cascade persisted. This means that by persisting any entity, ORM will automatically persist all of its associations.
You can control this behaviour via
cascade attribute of
New entities without primary key will be always persisted, regardless of
Here is example of how cascade persist works:
When cascade persisting collections, keep in mind only fully initialized collections will be cascade persisted.
When you want to merge entity and all its associations, you can use
comes handy when you want to clear identity map (e.g. when importing large number of entities),
but you also have to keep your parent entities managed (because otherwise they would be considered
as new entities and insert-persisted, which would fail with non-unique identifier).
In following example, without having
Author.favouriteBook set to cascade merge, you would
get an error because it would be cascade-inserted with already taken ID.
Cascade remove works same way as cascade persist, just for removing entities. Following
example assumes that
Book.publisher is set to
Note that cascade remove for collections can be inefficient as it will fire 1 query for each entity in collection.
Keep in mind that cascade remove can be dangerous when used on
as cascade removed entity can stay referenced in another entities that were not removed.
In addition to
Cascade.REMOVE, there is also additional and more aggressive remove
cascading mode which can be specified using the
orphanRemoval flag of the
orphanRemovalflag behaves just like
Cascade.REMOVEfor remove operation, so specifying both is redundant.
Cascade.REMOVE, you wound need to remove the
Author entity to cascade
the operation down to all loaded
Books. By enabling orphan removal on the collection,
Books will be also removed when they get disconnected from the collection (either via
remove(), or by replacing collection items via
In this example, no
Book would be removed with simple
Cascade.REMOVE as no remove operation
Declarative Referential Integrity
This is only supported in SQL drivers.
As opposed to the application level cascading controlled by the
cascade option, we can
also define database level referential integrity actions:
on update and
Their values are automatically inferred from the
cascade option value. You can also
control the value manually via