Stefan Haberl Stefan Haberl - 17 days ago 9
Java Question

Spring Data JPA and Exists query

I'm using Spring Data JPA (with Hibernate as my JPA provider) and want to define an

exists
method with a HQL query attached:

public interface MyEntityRepository extends CrudRepository<MyEntity, String> {

@Query("select count(e) from MyEntity e where ...")
public boolean existsIfBlaBla(@Param("id") String id);

}


When I run this query, I get a
java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.Boolean
.

How does the HQL query have to look like to make this work? I know I could simply return a Long value and afterwards check in my Java code if
count > 0
, but that workaround shouldn't be necessary, right?

Answer

I think you can simply change the query to return boolean as

@Query("select count(e)>0 from MyEntity e where ...")

PS: If you are checking exists based on Primary key value CrudRepository already have exists(id) method.

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