public final Enum LazyToOneOption

The association is always loaded eagerly. The identifier and concrete type of the associated entity instance, along with all the rest of its non-lazy fields, are always available immediately.

The associated entity instance is initially in an unloaded state, and is loaded lazily when any field other than the field containing the identifier is first accessed.

• The identifier field of an unloaded entity instance is set when the unloaded instance is instantiated. The program may obtain the identifier of an unloaded entity, without triggering lazy fetching, by accessing the field containing the identifier.
• Typecasts, the Java instanceof operator, and Object#getClass() may be used as normal.
• Bytecode enhancement is required. If the class is not enhanced, this option is equivalent to PROXY.

Hibernate does not support this setting for polymorphic associations, and instead falls back to PROXY.

The association is proxied and a delegate entity instance is lazily fetched when any method of the proxy other than the getter method for the identifier property is first called.

• The identifier property of the proxy object is set when the proxy is instantiated. The program may obtain the entity identifier value of an unfetched proxy, without triggering lazy fetching, by calling the corresponding getter method.
• The proxy does not have the same concrete type as the proxied delegate, and so org.hibernate.Hibernate#getClass(Object) must be used in place of Object#getClass(), and this method fetches the entity by side-effect.
• For a polymorphic association, the concrete type of the proxied entity instance is not known until the delegate is fetched from the database, and so org.hibernate.Hibernate#unproxy(Object, Class)} must be used to perform typecasts, and org.hibernate.Hibernate#getClass(Object) must be used instead of the Java instanceof operator.