[Week9][Chap4] Feat: 순수 JPA 페이징과 정렬 (#106)

김지윤/data-jpa/src/main/java/study/datajpa/repository/MemberJpaRepository.java

@@ -54,4 +54,18 @@ public List<Member> findByUsername(String username) {
                 .setParameter("username", username)
                 .getResultList();
     }
+
+    public List<Member> findByPage(int age, int offset, int limit) {
+        return em.createQuery("select m from Member m where m.age = :age order by m.username desc")
+                .setParameter("age", age)
+                .setFirstResult(offset)
+                .setMaxResults(limit)
+                .getResultList();
+    }
+
+    public long totalCount(int age) {
+        return em.createQuery("select count(m) from Member m where m.age = :age", Long.class)
+                .setParameter("age", age)
+                .getSingleResult();
+    }
 }

김지윤/data-jpa/src/test/java/study/datajpa/repository/MemberJpaRepositoryTest.java

@@ -87,4 +87,30 @@ public void testNamedQuery() {
         Member findMember = result.get(0);
         assertThat(findMember).isEqualTo(m1);
     }
+
+    @Test
+    public void paging() {
+        // given
+        memberJpaRepository.save(new Member("member1", 10));
+        memberJpaRepository.save(new Member("member2", 10));
+        memberJpaRepository.save(new Member("member3", 10));
+        memberJpaRepository.save(new Member("member4", 10));
+        memberJpaRepository.save(new Member("member5", 10));
+
+        int age = 10;
+        int offset = 0;
+        int limit = 3;
+
+        // when
+        List<Member> members = memberJpaRepository.findByPage(age, offset, limit);
+        long totalCount = memberJpaRepository.totalCount(age);
+
+        // 페이지 계산 공식 적용
+        // totalPage = totalCount / size
+
+        // then
+        assertThat(members.size()).isEqualTo(3);
+        assertThat(totalCount).isEqualTo(5);
+
+    }
 }