Hibernate JPA @Loader Example

@Loader

The @Loader annotation is used to override the default SELECT query used for loading an entity.

Loader

Used to override how Hibernate performs load operations. naming a named query to use instead of its generated SELECT SQL.

Custom CRUD

@Entity(name = "Person")
@SQLInsert(
sql = "INSERT INTO person (name, id, valid) VALUES (?, ?, true) ",
check = ResultCheckStyle.COUNT
)
@SQLUpdate(
sql = "UPDATE person SET name = ? where id = ? "
)
@SQLDelete(
sql = "UPDATE person SET valid = false WHERE id = ? "
)
@Loader(namedQuery = "find_valid_person")
@NamedNativeQueries({
@NamedNativeQuery(
name = "find_valid_person",
query = "SELECT id, name " +
"FROM person " +
"WHERE id = ? and valid = true",
resultClass = Person.class
)
})
public static class Person {

@Id
@GeneratedValue
private Long id;

private String name;

@ElementCollection
@SQLInsert(
sql = "INSERT INTO person_phones (person_id, phones, valid) VALUES (?, ?, true) ")
@SQLDeleteAll(
sql = "UPDATE person_phones SET valid = false WHERE person_id = ?")
@Where( clause = "valid = true" )
private List<String> phones = new ArrayList<>();

//Getters and setters are omitted for brevity

}
In the example above, the entity is mapped so that entries are soft-deleted (the records are not removed from the database, but instead, a flag marks the row validity). The Person entity benefits from custom INSERT, UPDATE, and DELETE statements which update the valid column accordingly. The custom @Loader is used to retrieve only Person rows that are valid.