How to use own query for save operation when extending crud repository?

Question

I'm extending CrudRepository of spring.data and using custom queries.

public interface CustomerRepo extends CrudRepository<Customer, Long> {

    @Query(value = "SELECT extract(isodow(birthday)) FROM customer WHERE id = :customer_id", nativeQuery = true)
    LocalTime findDayOfBirthById(@Param("customer_id") Long id);

Now I want to change the standard save method of the my Customer repo by using sql. I tried things like

    @Query(value = "insert into customer (birthday, name) values (birthday, name);", nativeQuery = true)
    Customer save(@Param("birthday") LocalDateTime bday, @Param("name") String name);

But it's not working. Any simple solution for overriding the standard save method with an own sql query? I'd like to know the general way how to do it.

The error I receive:

org.postgresql.util.PSQLException: The query does not return a result.
    at org.postgresql.jdbc.PgPreparedStatement.executeQuery(PgPreparedStatement.java:107) ~[postgresql-42.2.5.jar:42.2.5]
    at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeQuery(ProxyPreparedStatement.java:52) ~[HikariCP-3.2.0.jar:na]
    at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeQuery(HikariProxyPreparedStatement.java) ~[HikariCP-3.2.0.jar:na]
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:60) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.loader.Loader.getResultSet(Loader.java:2167) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1930) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1892) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.loader.Loader.doQuery(Loader.java:937) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:340) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.loader.Loader.doList(Loader.java:2689) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.loader.Loader.doList(Loader.java:2672) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2506) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.loader.Loader.list(Loader.java:2501) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:338) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.internal.SessionImpl.listCustomQuery(SessionImpl.java:2223) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.internal.AbstractSharedSessionContract.list(AbstractSharedSessionContract.java:1053) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.query.internal.NativeQueryImpl.doList(NativeQueryImpl.java:170) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1505) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.query.internal.AbstractProducedQuery.getSingleResult(AbstractProducedQuery.java:1553) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.springframework.data.jpa.repository.query.JpaQueryExecution$SingleEntityExecution.doExecute(JpaQueryExecution.java:214) ~[spring-data-jpa-2.1.2.RELEASE.jar:2.1.2.RELEASE]
    at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:91) ~[spring-data-jpa-2.1.2.RELEASE.jar:2.1.2.RELEASE]
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:136) ~[spring-data-jpa-2.1.2.RELEASE.jar:2.1.2.RELEASE]
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:125) ~[spring-data-jpa-2.1.2.RELEASE.jar:2.1.2.RELEASE]

It's obvious that it's not returning a result since it's in insert statement.

Answer 1

When you keep to the default behaviour a save will return your Customer object.

When you don't need to keep your Customer object and the database record in sync you can use

@Modifying
@Query(value = "insert into customer (birthday, name) values (birthday, name);", nativeQuery = true)
    void save(@Param("birthday") LocalDateTime bday, @Param("name") String name);

You can define your own extention on Repository for instance

@NoRepositoryBean
public interface ReadOnlyRepository<T, ID extends Serializable> extends Repository<T, ID> {

    T findOne(ID id);

    Iterable<T> findAll();

    Iterable<T> findAll(Sort sort);

    Page<T> findAll(Pageable pageable);
}

extent your CustomerRepo from this one and you don't have a default save method