Data JPA and Querydsl (Spring Boot)

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

Querydsl

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.

Spring Data Query by Example

Reference > https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#query-by-example

Examples

Delete

/**

* Delete by id.academic record

@Transactional

void deleteByNotifAcademicRecordId_AcademicRecordCode(Long academicRecordCode); // NOSONAR

Pagination

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());