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?
This question is related to
java
hibernate
jpa
spring-data
jpql
It's gotten a lot easier these days!
@Repository
public interface PageRepository extends JpaRepository<Page, UUID> {
Boolean existsByName(String name); //Checks if there are any records by name
Boolean existsBy(); // Checks if there are any records whatsoever
}
You can just return a Boolean like this:
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.jpa.repository.QueryHints;
import org.springframework.data.repository.query.Param;
@QueryHints(@QueryHint(name = org.hibernate.jpa.QueryHints.HINT_FETCH_SIZE, value = "1"))
@Query(value = "SELECT (1=1) FROM MyEntity WHERE ...... :id ....")
Boolean existsIfBlaBla(@Param("id") String id);
Boolean.TRUE.equals(existsIfBlaBla("0815"))
could be a solution
Since Spring data 1.12 you can use the query by Example functionnality by extending the QueryByExampleExecutor
interface (The JpaRepository
already extends it).
Then you can use this query (among others) :
<S extends T> boolean exists(Example<S> example);
Consider an entity MyEntity
which as a property name
, you want to know if an entity with that name exists, ignoring case, then the call to this method can look like this :
//The ExampleMatcher is immutable and can be static I think
ExampleMatcher NAME_MATCHER = ExampleMatcher.matching()
.withMatcher("name", GenericPropertyMatchers.ignoreCase());
Example<MyEntity> example = Example.<MyEntity>of(new MyEntity("example name"), NAME_MATCHER);
boolean exists = myEntityRepository.exists(example);
You can use .exists (return boolean) in jpaRepository.
if(commercialRuleMsisdnRepo.exists(commercialRuleMsisdn.getRuleId())!=true){
jsRespon.setStatusDescription("SUCCESS ADD TO DB");
}else{
jsRespon.setStatusCode("ID already exists is database");
}
You can use Case
expression for returning a boolean
in your select query like below.
@Query("SELECT CASE WHEN count(e) > 0 THEN true ELSE false END FROM MyEntity e where e.my_column = ?1")
in my case it didn't work like following
@Query("select count(e)>0 from MyEntity e where ...")
You can return it as boolean value with following
@Query(value = "SELECT CASE WHEN count(pl)> 0 THEN true ELSE false END FROM PostboxLabel pl ...")
Apart from the accepted answer, I'm suggesting another alternative.
Use QueryDSL, create a predicate and use the exists()
method that accepts a predicate and returns Boolean.
One advantage with QueryDSL is you can use the predicate for complicated where clauses.
Spring Data JPA 1.11 now supports the exists
projection in repository query derivation.
See documentation here.
In your case the following will work:
public interface MyEntityRepository extends CrudRepository<MyEntity, String> {
boolean existsByFoo(String foo);
}
Source: Stackoverflow.com