[SPRING] Querydsl | 스프링 데이터 JPA와 Querydsl

스프링 데이터 JPA

스프링 프레임워크에서 JPA를 편리하게 사용할 수 있도록 지원하는 모듈(인터페이스)로

데이터 접근 계층을 개발할 때 구현 클래스 없이 인터페이스만 작성해도 개발을 완료할 수 있도록 지원한다.

JPA와 영속성 → https://juran-devblog.tistory.com/5

[SPRING] JPA 프로그래밍 기본 | JPA와 영속성

JpaRepository

@NoRepositoryBean
public interface JpaRepository<T, ID> extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.CrudRepository#findAll()
	 */
	@Override
	List<T> findAll();

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.PagingAndSortingRepository#findAll(org.springframework.data.domain.Sort)
	 */
	@Override
	List<T> findAll(Sort sort);

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.CrudRepository#findAll(java.lang.Iterable)
	 */
	@Override
	List<T> findAllById(Iterable<ID> ids);

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.CrudRepository#save(java.lang.Iterable)
	 */
	@Override
	<S extends T> List<S> saveAll(Iterable<S> entities);

	/**
	 * Flushes all pending changes to the database.
	 */
	void flush();

	/**
	 * Saves an entity and flushes changes instantly.
	 *
	 * @param entity
	 * @return the saved entity
	 */
	<S extends T> S saveAndFlush(S entity);

	/**
	 * Deletes the given entities in a batch which means it will create a single {@link Query}. Assume that we will clear
	 * the {@link javax.persistence.EntityManager} after the call.
	 *
	 * @param entities
	 */
	void deleteInBatch(Iterable<T> entities);

	/**
	 * Deletes all entities in a batch call.
	 */
	void deleteAllInBatch();

	/**
	 * Returns a reference to the entity with the given identifier. Depending on how the JPA persistence provider is
	 * implemented this is very likely to always return an instance and throw an
	 * {@link javax.persistence.EntityNotFoundException} on first access. Some of them will reject invalid identifiers
	 * immediately.
	 *
	 * @param id must not be {@literal null}.
	 * @return a reference to the entity with the given identifier.
	 * @see EntityManager#getReference(Class, Object) for details on when an exception is thrown.
	 */
	T getOne(ID id);

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.query.QueryByExampleExecutor#findAll(org.springframework.data.domain.Example)
	 */
	@Override
	<S extends T> List<S> findAll(Example<S> example);

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.query.QueryByExampleExecutor#findAll(org.springframework.data.domain.Example, org.springframework.data.domain.Sort)
	 */
	@Override
	<S extends T> List<S> findAll(Example<S> example, Sort sort);
}

 

MemberRepository

import org.springframework.data.jpa.repository.JpaRepository;

public interface MemberRepository extends JpaRepository<Member, Long> {

    List<Member> findByUsername(String username);
}

간단히 메서드명 작성으로 메서드 구현 완료

 

사용자 정의 레퍼지토리

spring data jpa 인터페이스와 사용자가 정의한 querydsl 같이 사용하기

1) 사용자 정의 레퍼지토리 작성 - MemberRepositoryCustom(Interface)

public interface MemberRepositoryCustom {

    List<MemberTeamDto> search(MemberSearchCondition condition);
}

querydsl로 작성할 메서드 정의

 

2) 사용자 정의 레퍼지토리 구현 - MemberRepositoryImpl(Class)

public class MemberRepositoryImpl implements MemberRepositoryCustom{

    private final JPAQueryFactory queryFactory;
    public MemberRepositoryImpl(EntityManager em) {
        this.queryFactory = new JPAQueryFactory(em);
    }

    @Override
    public List<MemberTeamDto> search(MemberSearchCondition condition) {
        return queryFactory
                .select(new QMemberTeamDto(
                        member.id.as("memberId"),
                        member.username,
                        member.age,
                        team.id.as("teamId"),
                        team.name.as("teamName")
                ))
                .from(member)
                .leftJoin(member.team, team)
                .where(usernameEq(condition.getUsername()),
                        teamNameEq(condition.getTeamName()),
                        ageGoe(condition.getAgeGoe()),
                        ageLoe(condition.getAgeLoe()))
                .fetch();
    }

    private BooleanExpression usernameEq(String username) {
        return hasText(username) ? member.username.eq(username) : null;
    }

    private BooleanExpression teamNameEq(String teamName) {
        return hasText(teamName) ? team.name.eq(teamName) : null;
    }

    private BooleanExpression ageGoe(Integer ageGoe) {
        return ageGoe != null ? member.age.goe(ageGoe) : null;
    }

    private Predicate ageLoe(Integer ageLoe) {
        return ageLoe != null ? member.age.loe(ageLoe) : null;
    }
}

MemberRepositoryCustom에서 정의한 메서드 오버라이딩

 

3) 스프링 데이터 레퍼지토리에 사용자 정의 레퍼지토리 상속

public interface MemberRepository extends JpaRepository<Member, Long>, MemberRepositoryCustom {

    List<Member> findByUsername(String username);
}