Spring repository interface: query methods by type

Question

I wonder if it is possible to specify a specific subtype with springs' query methods.

For example, if there is a MailUser and ChatUser, both extend User with InheritanceType.SINGLE_TABLE - can I find all MailUsers with the PersonRepository?

Or can I find all Users excluding all MailUsers in a scenario where multiple classes extend User?

public interface PersonRepository extends Repository<User, Long> {

  List<Person> findByEmailAddressAndLastname(EmailAddress emailAddress, String lastname);
...
}

Answer 1

You cannot do it with the automatic query creation based on the method names, Spring Data does not support it (see here for the supported expressions). However, you can use @Query to specify a JPQL query by hand and use the TYPE(entity) operator in the WHERE clause to narrow down to a particular entity type. See JPA spec 4.6.17.5 Entity Type Expressions:

An entity type expression can be used to restrict query polymorphism. The TYPE operator returns the exact type of the argument.

[...]

Examples:

SELECT e
FROM Employee e
WHERE TYPE(e) IN (Exempt, Contractor)

SELECT e
FROM Employee e
WHERE TYPE(e) IN (:empType1, :empType2)

SELECT e
FROM Employee e
WHERE TYPE(e) IN :empTypes

SELECT TYPE(e)
FROM Employee e
WHERE TYPE(e) <> Exempt