[BE] refactor: 놀이터 상세조회 쿼리 반복 호출 개선

backend/src/main/java/com/happy/friendogly/pet/repository/PetRepository.java

@@ -35,4 +35,12 @@ default Pet getById(Long id) {
     boolean existsByMemberId(Long memberId);
 
     void deleteAllByMemberId(Long memberId);
+
+    @Query("""
+            SELECT p
+            FROM Pet p
+            WHERE p.member.id
+            IN :memberIds
+            """)
+    List<Pet> findAllByMemberIds(List<Long> memberIds);
 }

backend/src/main/java/com/happy/friendogly/playground/service/PlaygroundQueryService.java

@@ -13,9 +13,12 @@
 import com.happy.friendogly.playground.repository.PlaygroundMemberRepository;
 import com.happy.friendogly.playground.repository.PlaygroundRepository;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
+import java.util.Map;
 import java.util.Optional;
+import java.util.stream.Collectors;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -40,19 +43,24 @@ public PlaygroundQueryService(
     }
 
     public FindPlaygroundDetailResponse findDetail(Long callMemberId, Long playgroundId) {
-        Playground playground = playgroundRepository.getById(playgroundId);
         List<PlaygroundMember> playgroundMembers = playgroundMemberRepository.findAllByPlaygroundId(playgroundId);
 
         int totalPetCount = 0;
         int arrivedPetCount = 0;
 
-        List<PlaygroundPetDetail> playgroundPetDetails = new ArrayList<>();
+        List<Long> memberIds = playgroundMembers.stream()
+                .map(playgroundMember -> playgroundMember.getMember().getId())
+                .toList();
+
+        Map<Long, List<Pet>> memberPets = petRepository.findAllByMemberIds(memberIds).stream()
+                .collect(Collectors.groupingBy(pet -> pet.getMember().getId()));
 
+        List<PlaygroundPetDetail> playgroundPetDetails = new ArrayList<>();
         for (PlaygroundMember playgroundMember : playgroundMembers) {
             Member member = playgroundMember.getMember();
             boolean isMyPet = member.getId().equals(callMemberId);
 
-            List<Pet> pets = petRepository.findByMemberId(member.getId());
+            List<Pet> pets = memberPets.getOrDefault(member.getId(), Collections.emptyList());
             totalPetCount += pets.size();
             arrivedPetCount += getArrivedPetCount(playgroundMember, pets);
 
@@ -70,7 +78,7 @@ public FindPlaygroundDetailResponse findDetail(Long callMemberId, Long playgroun
                 .anyMatch(playgroundMember -> playgroundMember.equalsMemberId(callMemberId));
 
         return new FindPlaygroundDetailResponse(
-                playground.getId(),
+                playgroundId,
                 totalPetCount,
                 arrivedPetCount,
                 isParticipating,

backend/src/test/java/com/happy/friendogly/pet/repository/PetRepositoryTest.java

@@ -0,0 +1,64 @@
+package com.happy.friendogly.pet.repository;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
+
+import com.happy.friendogly.member.domain.Member;
+import com.happy.friendogly.member.repository.MemberRepository;
+import com.happy.friendogly.pet.domain.Gender;
+import com.happy.friendogly.pet.domain.Pet;
+import com.happy.friendogly.pet.domain.SizeType;
+import java.time.LocalDate;
+import java.util.List;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
+
+@DataJpaTest
+class PetRepositoryTest {
+
+    @Autowired
+    MemberRepository memberRepository;
+    @Autowired
+    PetRepository petRepository;
+
+    @DisplayName("다수의 멤버 ID로 멤버들의 펫을 조회할 수 있다.")
+    @Disabled
+    @Test
+    void findAllByMemberIdIn() {
+        // given
+        Member savedMember1 = memberRepository.save(new Member("member1", "tag1", "imageUrl1"));
+        Member savedMember2 = memberRepository.save(new Member("member2", "tag2", "imageUrl2"));
+        petRepository.save(
+                new Pet(
+                        savedMember1,
+                        "name1",
+                        "description1",
+                        LocalDate.now(),
+                        SizeType.LARGE,
+                        Gender.FEMALE,
+                        "imageUrl1"
+                )
+        );
+        petRepository.save(
+                new Pet(
+                        savedMember2,
+                        "name2",
+                        "description2",
+                        LocalDate.now(),
+                        SizeType.LARGE,
+                        Gender.FEMALE,
+                        "imageUrl2"
+                )
+        );
+
+        // when
+        List<Pet> pets = petRepository.findAllByMemberIds(
+                List.of(savedMember1.getId(), savedMember2.getId()));
+
+        // then
+        assertThat(pets).hasSize(2);
+    }
+}