[QueryDSL] 동적 쿼리

동적 쿼리

동적 쿼리를 해결하는 두가지 방식

1. BooleanBuilder
2. Where 다중 파라미터 사용

1. BooleanBuilder 사용

@Test
public void dynamicQuery_BooleanBuilder() {
    String usernameParam = "member1";
    Integer ageParam = 10;

    List<Member> result = searchMember1(usernameParam, ageParam);
    Assertions.assertThat(result.size()).isEqualTo(1);
}

private List<Member> searchMember1(String usernameCond, Integer ageCond) {

    BooleanBuilder builder = new BooleanBuilder();
    if (usernameCond != null) {
        builder.and(member.username.eq(usernameCond));
    }
    if (ageCond != null) {
        builder.and(member.age.eq(ageCond));
    }
    return queryFactory
            .selectFrom(member)
            .where(builder)
            .fetch();
}

 

2. Where 다중 파라미터 사용

@Test
public void dynamicQuery_WhereParam() {
    String usernameParam = "member1";
    Integer ageParam = 10;

    List<Member> result = searchMember2(usernameParam, ageParam);
    Assertions.assertThat(result.size()).isEqualTo(1);
}

private List<Member> searchMember2(String usernameCond, Integer ageCond) {
    return queryFactory
            .selectFrom(member)
            .where(usernameEq(usernameCond), ageEq(ageCond))
            .fetch();
}

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

private BooleanExpression ageEq(Integer ageCond) {
    return ageCond != null ? member.age.eq(ageCond) : null;
}

• where 조건에 null 값은 무시된다.
• 메서드를 다른 쿼리에서도 재활용 할 수 있다.
• 쿼리 자체의 가독성이 높아진다.

✅ 조합 가능

private List<Member> searchMember2(String usernameCond, Integer ageCond) {
    return queryFactory
            .selectFrom(member)
            // .where(usernameEq(usernameCond), ageEq(ageCond))
            .where(allEq(usernameCond, ageCond))
            .fetch();
}

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

private BooleanExpression ageEq(Integer ageCond) {
    return ageCond != null ? member.age.eq(ageCond) : null;
}

// 추가
private BooleanExpression allEq(String usernameCond, Integer ageCond) {
    return usernameEq(usernameCond).and(ageEq(ageCond));
}

• null 체크는 주의해서 처리해야함

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