querydsl : projection, dynamic query, bulk update, sql function

querydsl/src/main/java/com/example/querydsl/dto/MemberDto.java

@@ -0,0 +1,20 @@
+package com.example.querydsl.dto;
+
+import com.querydsl.core.annotations.QueryProjection;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@NoArgsConstructor
+public class MemberDto {
+
+    private String username;
+    private int age;
+
+    @QueryProjection
+    public MemberDto(String username, int age) {
+        this.username = username;
+        this.age = age;
+    }
+}

querydsl/src/main/java/com/example/querydsl/dto/UserDto.java

@@ -0,0 +1,9 @@
+package com.example.querydsl.dto;
+
+import lombok.Data;
+
+@Data
+public class UserDto {
+    private String name;
+    private int age;
+}

querydsl/src/test/java/com/example/querydsl/QuerydslBasicTest.java

@@ -1,11 +1,19 @@
 package com.example.querydsl;
 
+import com.example.querydsl.dto.MemberDto;
+import com.example.querydsl.dto.QMemberDto;
+import com.example.querydsl.dto.UserDto;
 import com.example.querydsl.entity.Member;
 import com.example.querydsl.entity.QMember;
 import com.example.querydsl.entity.QTeam;
 import com.example.querydsl.entity.Team;
+import com.querydsl.core.BooleanBuilder;
 import com.querydsl.core.QueryResults;
 import com.querydsl.core.Tuple;
+import com.querydsl.core.types.ExpressionUtils;
+import com.querydsl.core.types.Predicate;
+import com.querydsl.core.types.Projections;
+import com.querydsl.core.types.dsl.BooleanExpression;
 import com.querydsl.core.types.dsl.CaseBuilder;
 import com.querydsl.core.types.dsl.Expressions;
 import com.querydsl.jpa.JPAExpressions;
@@ -15,6 +23,7 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.annotation.Commit;
 import org.springframework.transaction.annotation.Transactional;
 
 import javax.persistence.EntityManager;
@@ -448,4 +457,279 @@ public class QuerydslBasicTest {
             System.out.println("s = " + s);
         }
     }
+
+    @Test
+    void simpleProjection() {
+        List<String> result = queryFactory
+                .select(member.username)
+                .from(member)
+                .fetch();
+
+        for (String s : result) {
+            System.out.println("s = " + s);
+        }
+    }
+
+    @Test
+    void tupleProjection() {
+        List<Tuple> result = queryFactory
+                .select(member.username, member.age)
+                .from(member)
+                .fetch();
+
+        for (Tuple tuple : result) {
+            String username = tuple.get(member.username);
+            Integer age = tuple.get(member.age);
+            System.out.println("username = " + username);
+            System.out.println("age = " + age);
+        }
+    }
+
+    @Test
+    void findDtoByJPQL() {
+        List<MemberDto> result =
+                em.createQuery("select new com.example.querydsl.dto.MemberDto(m.username, m.age) from Member m", MemberDto.class)
+                .getResultList();
+
+        for (MemberDto memberDto : result) {
+            System.out.println("memberDto = " + memberDto);
+        }
+    }
+
+    @Test
+    void findDtoBySetter() {
+        List<MemberDto> result = queryFactory
+                .select(Projections.bean(MemberDto.class,
+                        member.username,
+                        member.age))
+                .from(member)
+                .fetch();
+
+        for (MemberDto memberDto : result) {
+            System.out.println("memberDto = " + memberDto);
+        }
+    }
+
+    @Test
+    void findDtoByField() {
+        List<MemberDto> result = queryFactory
+                .select(Projections.fields(MemberDto.class,
+                        member.username,
+                        member.age))
+                .from(member)
+                .fetch();
+
+        for (MemberDto memberDto : result) {
+            System.out.println("memberDto = " + memberDto);
+        }
+    }
+
+    @Test
+    void findDtoByConstructor() {
+        List<MemberDto> result = queryFactory
+                .select(Projections.constructor(MemberDto.class, // 생성자는 타입으로 매칭 이름 달라도 됨
+                        member.username,
+                        member.age))
+                .from(member)
+                .fetch();
+
+        for (MemberDto memberDto : result) {
+            System.out.println("memberDto = " + memberDto);
+        }
+    }
+
+    @Test
+    void findUserDto() {
+        List<UserDto> result = queryFactory
+                .select(Projections.fields(UserDto.class,
+                        member.username.as("name"),
+                        member.age))
+                .from(member)
+                .fetch();
+
+        for (UserDto userDto : result) {
+            System.out.println("userDto = " + userDto);
+        }
+    }
+
+    @Test
+    void findUserDtoAlias() {
+        QMember memberSub = new QMember("memberSub");
+        List<UserDto> result = queryFactory
+                .select(Projections.fields(UserDto.class,
+                        member.username.as("name"),
+                        ExpressionUtils.as(JPAExpressions
+                                .select(memberSub.age.max())
+                                .from(memberSub), "age")
+                        ))
+                .from(member)
+                .fetch();
+
+        for (UserDto userDto : result) {
+            System.out.println("userDto = " + userDto);
+        }
+    }
+
+    @Test
+    void findDtoByQueryProjection() {
+        List<MemberDto> result = queryFactory
+                .select(new QMemberDto(member.username, member.age))
+                .from(member)
+                .fetch();
+
+        for (MemberDto memberDto : result) {
+            System.out.println("memberDto = " + memberDto);
+        }
+    }
+
+    @Test
+    void dynamicQuery_booleanBuilder() {
+        String usernameParam = "member1";
+        Integer ageParam = 10;
+
+        List<Member> result = searchMember1(usernameParam, ageParam);
+        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();
+    }
+
+    @Test
+    void dynamicQuery_WhereParam() {
+        String usernameParam = "member1";
+        Integer ageParam = null;
+
+        List<Member> result = searchMember2(usernameParam, ageParam);
+        assertThat(result.size()).isEqualTo(1);
+    }
+
+    private List<Member> searchMember2(String usernameCond, Integer ageCond) {
+
+        return queryFactory
+                .selectFrom(member)
+                .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;
+    }
+
+    private BooleanExpression allEq(String usernameCond, Integer ageCond) {
+        return usernameEq(usernameCond).and(ageEq(ageCond));
+    }
+
+    @Test
+    void bulkUpdate() {
+
+        // bulk update 는 영속성 컨텍스트에는 값이 변하지 않고 남아있다.
+        // 변경하고 DB에서 다시 조회를 하더라도 영속성 컨텍스트에 이미 값이 있기 때문에
+        // 영속성 컨텍스트의 값이 우선권을 가진다.
+        long count = queryFactory
+                .update(member)
+                .set(member.username, "비회원")
+                .where(member.age.lt(28))
+                .execute();
+
+        List<Member> result = queryFactory
+                .selectFrom(member)
+                .fetch();
+
+        for (Member member1 : result) {
+            System.out.println("member1 = " + member1);
+        }
+
+        // 벌크 연산 후에는 초기화를 하는 것이 좋다.
+        em.flush();
+        em.clear();
+
+        result = queryFactory
+                .selectFrom(member)
+                .fetch();
+
+        for (Member member1 : result) {
+            System.out.println("member1 = " + member1);
+        }
+    }
+
+    @Test
+    void bulkAdd() {
+        long cnt = queryFactory
+                .update(member)
+                .set(member.age, member.age.add(1))
+                .execute();
+        em.flush();
+        em.clear();
+        List<Member> result = queryFactory
+                .selectFrom(member)
+                .fetch();
+
+        for (Member member1 : result) {
+            System.out.println("member1 = " + member1);
+        }
+    }
+
+    @Test
+    void bulkDelete() {
+        long cnt = queryFactory
+                .delete(member)
+                .where(member.age.gt(18))
+                .execute();
+
+        em.flush();
+        em.clear();
+        List<Member> result = queryFactory
+                .selectFrom(member)
+                .fetch();
+
+        for (Member member1 : result) {
+            System.out.println("member1 = " + member1);
+        }
+    }
+
+    @Test
+    void sqlFunction() {
+        List<String> result = queryFactory
+                .select(Expressions.stringTemplate(
+                        "function('replace', {0}, {1}, {2})",
+                        member.username, "member", "M"))
+                .from(member)
+                .fetch();
+
+        for (String s : result) {
+            System.out.println("s = " + s);
+        }
+    }
+
+    @Test
+    void sqlFunction2() {
+        List<String> result = queryFactory
+                .select(member.username)
+                .from(member)
+//                .where(member.username.eq(
+//                        Expressions.stringTemplate("function('lower', {0})", member.username)))
+                .where(member.username.eq(member.username.lower()))
+                .fetch();
+
+        for (String s : result) {
+            System.out.println("s = " + s);
+        }
+    }
 }