Hibernate - A collection with cascade=”all-delete-orphan” was no longer referenced by the owning entity instance
Hibernate has a pet peeve. It grumbles when you replace a cascade=all-delete-orphan collection completely. So if you try setting a new List (AKA: parent.setChildren(new ArrayList<>())), be prepared for a Hibernate tantrum. The secret to keeping it happy is to cherish the original collection reference like your favorite coffee cup. To replace the contents, simply do some spring cleaning with .clear() (parent.getChildren().clear()) and then invite new occupants in with .addAll() (parent.getChildren().addAll(newChildren)). This is the 5-star service Hibernate expects to keep its orphan deletion contract content.
The Lifecycle of Your Little Beans (Child Entities)
Be the puppet master
Master the lifecycle of child entities that are part of a collection with cascade="all-delete-orphan". Like an experienced puppet master pulling the right strings, manipulate the existing collection, maintaining its integrity and syncing with Hibernate's lifecycle trails.
Create a bulletproof entity
Forge your equals and hashCode implementations to be as solid as an armadillo's armor. This will preserve identity and block accidental orphan deletion. A mistake here could make your data disappear like cookies at a toddler's birthday party.
Craft a well-oiled entity management
Embed add/remove methods directly into the parent entity to handle your child entities. Now you can avoid collection reassignment issues as smoothly as ice skaters dodge each other during a show.
Explanation
- New Connection (↔️): Engine has switched tracks and now pulls a new collection (not the initial 🚃s)
- Gone Carriages (💨🗑️): the older items have vanished because of
all-delete-orphan- they’ve been orphaned.
Key Idea: An engine can't be tied to two sets of carriages at once. The entity makes the call of which carriages to keep, leaving behind the others.
Collection Care Essentials
Never lose your hold
Always keep a firm grip on the parent-to-child collection reference. A slip-up here can lead to all-delete-orphan mayhem.
Beware of old ghosts (legacy code)
Watch out for collection reassignment sneakily hiding in legacy code. Review regularly and exercise defensive coding techniques like a knight wielding a shield and sword against dragons.
Hibernate's special goodies
Unwrap the power of Hibernate's special collection classes, such as PersistentSet or PersistentList. They’ve been meticulously crafted to flourish your entity handling.
Fend off unwanted deletions
Before you dive into handling collections, do some basic safety checks. Null checks, retainAll and addAll maneuvers can help keep your data float in collection waves without accidentally being pulled under.
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