Entities

Kotlin JDSL has the Entity interface to represent an entity in JPQL. Use entity() to build Entity.

entity(Book::class)

Alias

All Entity has an alias. If you don't specify an alias in entity(), Kotlin JDSL automatically generates an alias from the class name. Entity is identified by its alias. If you use more than one Entity with the same type, you need to alias them to identify each Entity.

entity(Book::class)
entity(Book::class, Book::class.simpleName!!)

entity(Book::class, alias = "book1")
entity(Book::class, alias = "book2")

Expression

Entity can be used as Expression in a select clause or predicate.

// SELECT b FROM Book AS b WHERE b.isbn.value = :param1
jpql {
    select(
        entity(Book::class, "b"),
    ).from(
        entity(Book::class, "b"),
    ).where(
        entity(Book::class, "b")(Book::isbn)(Ibsn::value).eq("01"),
    )
}

Treat

Use treat() to typecast Entity to subclass.

entity(Employee::class).treat(FullTimeEmployee::class)