인프런 커뮤니티 질문&답변

1.

이렇게 했을 때 페이지 처리와 정렬이 되었습니다. 여기서 정적으로 하려면 지금 작성한 것처럼 지정해주고 orderBy를 동적으로 처리하려면 동적쿼리 where절 처럼 메소드를 만들어서 MemberSearchCondition같은 곳에 정렬을 받아서 메소드로 만들고 orderBy에 넣어주면 되나요??

2.

Querydsl4RepositorySupport

@Repository
public abstract class Querydsl4RepositorySupport {
    private final Class domainClass;
    private Querydsl querydsl;
    private EntityManager entityManager;
    private JPAQueryFactory queryFactory;
    public Querydsl4RepositorySupport(Class<?> domainClass) {
        Assert.notNull(domainClass, "Domain class must not be null!");
        this.domainClass = domainClass;
    }
    @Autowired
    public void setEntityManager(EntityManager entityManager) {
        Assert.notNull(entityManager, "EntityManager must not be null!");
        JpaEntityInformation entityInformation =
                JpaEntityInformationSupport.getEntityInformation(domainClass, entityManager);
        SimpleEntityPathResolver resolver = SimpleEntityPathResolver.INSTANCE;
        EntityPath path = resolver.createPath(entityInformation.getJavaType());
        this.entityManager = entityManager;
        this.querydsl = new Querydsl(entityManager, new
                PathBuilder<>(path.getType(), path.getMetadata()));
        this.queryFactory = new JPAQueryFactory(entityManager);
    }
    @PostConstruct
    public void validate() {
        Assert.notNull(entityManager, "EntityManager must not be null!");
        Assert.notNull(querydsl, "Querydsl must not be null!");
        Assert.notNull(queryFactory, "QueryFactory must not be null!");
    }
    protected JPAQueryFactory getQueryFactory() {
        return queryFactory;
    }
    protected Querydsl getQuerydsl() {
        return querydsl;
    }
    protected EntityManager getEntityManager() {
        return entityManager;
    }
    protected <T> JPAQuery<T> select(Expression<T> expr) {
        return getQueryFactory().select(expr);
    }
    protected <T> JPAQuery<T> selectFrom(EntityPath<T> from) {
        return getQueryFactory().selectFrom(from);
    }
    protected <T> Page<T> applyPagination(Pageable pageable,
                                          Function<JPAQueryFactory, JPAQuery> contentQuery) {
        JPAQuery jpaQuery = contentQuery.apply(getQueryFactory());
        List<T> content = getQuerydsl().applyPagination(pageable,
                jpaQuery).fetch();
        return PageableExecutionUtils.getPage(content, pageable,
                jpaQuery::fetchCount);
    }
    protected <T> Page<T> applyPagination(Pageable pageable,
                                          Function<JPAQueryFactory, JPAQuery> contentQuery, Function<JPAQueryFactory,
            JPAQuery> countQuery) {
        JPAQuery jpaContentQuery = contentQuery.apply(getQueryFactory());
        List<T> content = getQuerydsl().applyPagination(pageable,
                jpaContentQuery).fetch();
        JPAQuery countResult = countQuery.apply(getQueryFactory());
        return PageableExecutionUtils.getPage(content, pageable,
                countResult::fetchCount);
    }

}

 여기서 보면 fetchCount를 사용하고 있는데 deprecated가 뜹니다. 이거를 어떻게 수정해줘야 할까요?

3. Querydsl4RepositorySupport을 사용해서

    public Page<Member> applyPagination(MemberSearchCondition condition, Pageable pageable) {
        return applyPagination(pageable, query ->
                query.selectFrom(member)
                        .leftJoin(member.team, team)
                        .where(userNameEq(condition.getUserName()),
                                teamNameEq(condition.getTeamName()),
                                ageGoe(condition.getAgeGoe()),
                                ageLoe(condition.getAgeLoe())
                        )
        );
    }

    public Page<Member> applyPagination2(MemberSearchCondition condition, Pageable pageable) {
        return applyPagination(pageable, contentQuery ->
                contentQuery.selectFrom(member)
                        .leftJoin(member.team, team)
                        .where(userNameEq(condition.getUserName()),
                                teamNameEq(condition.getTeamName()),
                                ageGoe(condition.getAgeGoe()),
                                ageLoe(condition.getAgeLoe())
                        ), countQuery -> countQuery
                .select(member.id)
                .from(member)
                .where(userNameEq(condition.getUserName()),
                        teamNameEq(condition.getTeamName()),
                        ageGoe(condition.getAgeGoe()),
                        ageLoe(condition.getAgeLoe()))
        );
    }

이렇게 구현한 거에도 1번과 같이 메소드로 orderBy에 넣으면 되는건가요?

4. 1번과 3번의 차이는 코드를 더 가독성있게 하려고 하는건가요 아니면 성능상의 차이점이라던지 더 큰 장점이 있나요?