For Spring Data JPA Projections, see page 'Data JPA':
https://sites.google.com/site/pawneecity/sprint-boot/data-jpa-spring-boot
Spring Data JPA - Reference Documentation
See 'Query Methods' (section 6.3)
https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#reference
REST Query Language with Spring Data JPA and Querydsl (Baeldung)
https://www.baeldung.com/rest-api-search-language-spring-data-querydsl
Querydsl Reference Guide
http://www.querydsl.com/static/querydsl/latest/reference/html_single/
The annotation can only be used in instance (non-static) methods of Beans (Services, Components, etc.).
Warning: Since Spring proxies the class, the method must be invoked from another class to take effect!
Reference > https://www.wilfriedbarth.com/til/2018-03-31-spring-transactional-annotation/
Error:
No EntityManager with actual transaction available for current thread - cannot reliably process 'remove' call; nested exception is javax.persistence.TransactionRequiredException
Apparently, Spring only marks the default methods of the CrudRepository interface as transactional, so any custom methods that you define yourself won't be managed by the EntityManager. The fix for this is quite simple. Just mark the custom method with @Transactional and the EntityManager will recognize it as a transaction.
import org.springframework.transaction.annotation.Transactional;
/**
* Delete by academic record
*/
@Modifying
@Transactional
void deleteByNotifAcademicRecordId_AcademicRecordCode(Long academicRecordCode); // NOSONAR
Note:
findById(id) retrieves an entity -- Avoids the no Session exception in unit tests
getOne(id) returns a reference to the entity -- no Session exception in unit tests
There is an incompatibility with Java 11 and plugin com.mysema.maven:apt-maven-plugin:1.1.3 that deletes generated files.
Workaround: Use plugin version 1.1.2 instead.
Reference > https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#query-by-example
/**
* Delete by id.academic record
*/
@Transactional
void deleteByNotifAcademicRecordId_AcademicRecordCode(Long academicRecordCode); // NOSONAR
We can choose to return either a Page<T>, a Slice<T> or a List<T> from any of our custom methods returning a paginated data. A Page<T> also knows the total number of available pages, using an additional count query.
It also, optionally, supports sorting.
Repo method:
Slice<Milestone> findByMilestoneGatStatusNot(final String milestoneGatStatusCode, Pageable pageable);
Usage:
Slice<Milestone> slice;
int pageIndex = 0;
do {
Pageable pageable = PageRequest.of(pageIndex, 1024);
slice = this.milestoneRepo.findByMilestoneGatStatusNot(
milestoneAchievedStatusCode, pageable);
List<Milestone> records = slice.getContent();
/* whatever */
//Increase page index
pageIndex++;
} while (slice.hasNext());
-