2023-06-21-TIL

Today I Learned

https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#jpa.entity-persistence.saving-entites

https://spring.io/blog/2021/09/09/spring-data-jdbc-how-to-use-custom-id-generation
https://github.com/spring-projects/spring-data-examples/tree/main/jdbc/howto/idgeneration
https://thorben-janssen.com/custom-sequence-based-idgenerator/
https://yoonbing9.tistory.com/39

https://stackoverflow.com/questions/26313044/preferred-way-to-implement-persistable-isnew-for-entity-with-predefined-id-in-sp
https://docs.spring.io/spring-data/commons/docs/current/api/org/springframework/data/domain/Persistable.html
https://leegicheol.github.io/jpa/jpa-is-new/
https://catsbi.oopy.io/69a3e741-f165-4046-a6eb-2002143e5dae
https://neate.dev/technology/java/2020/04/15/using-persistable-for-jpa-performance-improvements.html
https://thorben-janssen.com/spring-data-jpa-state-detection/
https://jaime-note.tistory.com/65
https://thorben-janssen.com/spring-data-jpa-state-detection/

https://docs.jboss.org/hibernate/orm/5.2/javadocs/org/hibernate/engine/spi/SharedSessionContractImplementor.html
https://docs.jboss.org/hibernate/orm/current/javadocs/org/hibernate/engine/spi/SharedSessionContractImplementor.html
https://javadoc.io/static/org.hibernate/hibernate-core/5.4.9.Final/org/hibernate/engine/spi/SharedSessionContractImplementor.html

https://gmoon92.github.io/jpa/2019/09/29/what-is-the-transient-annotation-used-for-in-jpa.html
https://stackoverflow.com/questions/2154622/why-does-jpa-have-a-transient-annotation
https://www.baeldung.com/jpa-transient-ignore-field

엔티티 자체가 빈으로 등록되는게 아니므로 강제로 DB 커넥션에 대한 세션을 얻어와서 쿼리를 실행시켜야 한다. 하지만 이는 JPA의 영속계층에 대한 보호를 받지 못한다. 따라서 엔티티 안에서는 쿼리를 사용하지 않는 것이 좋다.

https://www.baeldung.com/spring-inject-bean-into-unmanaged-objects
https://stackoverflow.com/questions/12742826/how-do-i-know-the-id-before-saving-an-object-in-jpa