Hibernate JPA @DiscriminatorOptions Example

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@DiscriminatorOptions

The @DiscriminatorOptions annotation is used to provide the force and insert Discriminator properties.

DiscriminatorOptions Optional annotation to express Hibernate specific discriminator properties.

Discriminator
The discriminator column contains marker values that tell the persistence layer what subclass to instantiate for a particular row. Hibernate Core supports the following restricted set of types as discriminator column: String, char, int, byte, short, boolean(including yes_no, true_false).

Use the @DiscriminatorColumn to define the discriminator column as well as the discriminator type.

The enum DiscriminatorType used in javax.persistence.DiscriminatorColumn only contains the values STRING, CHAR and INTEGER which means that not all Hibernate supported types are available via the @DiscriminatorColumn annotation. You can also use @DiscriminatorFormula to express in SQL a virtual discriminator column. This is particularly useful when the discriminator value can be extracted from one or more columns of the table. Both @DiscriminatorColumn and @DiscriminatorFormula are to be set on the root entity (once per persisted hierarchy).

@org.hibernate.annotations.DiscriminatorOptions allows to optionally specify Hibernate-specific discriminator options which are not standardized in JPA. The available options are force and insert.

The force attribute is useful if the table contains rows with extra discriminator values that are not mapped to a persistent class. This could, for example, occur when working with a legacy database. If force is set to true, Hibernate will specify the allowed discriminator values in the SELECT query even when retrieving all instances of the root class.

The second option, insert, tells Hibernate whether or not to include the discriminator column in SQL INSERTs. Usually, the column should be part of the INSERT statement, but if your discriminator column is also part of a mapped composite identifier you have to set this option to false.

There used to be a @org.hibernate.annotations.ForceDiscriminator annotation which was deprecated in version 3.6 and later removed. Use @DiscriminatorOptions instead.

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