[feat/#111] 문항에 포함된 새끼문항ID들 조회

src/main/java/com/moplus/moplus_server/client/problem/controller/ProblemGetController.java

@@ -2,6 +2,7 @@
 
 import com.moplus.moplus_server.client.problem.dto.response.AllProblemGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ChildProblemClientGetResponse;
+import com.moplus.moplus_server.client.problem.dto.response.ChildProblemsClientGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ProblemClientGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ProblemClientThumbnailResponse;
 import com.moplus.moplus_server.client.problem.dto.response.PublishClientGetResponse;
@@ -75,4 +76,13 @@ public ResponseEntity<ProblemClientThumbnailResponse> getProblemThumbnail(
     ) {
         return ResponseEntity.ok(problemsGetService.getProblemThumbnail(publishId, problemId));
     }
+
+    @GetMapping("problem/child/{publishId}/{problemId}")
+    @Operation(summary = "문항에 포함된 새끼문항 정보 조회", description = "단계별로 풀어보기 이후 화면들에서 필요한 정보들을 조회합니다.")
+    public ResponseEntity<ChildProblemsClientGetResponse> getChildProblems(
+            @PathVariable Long publishId,
+            @PathVariable Long problemId
+    ) {
+        return ResponseEntity.ok(problemsGetService.getChildProblems(publishId, problemId));
+    }
 }

src/main/java/com/moplus/moplus_server/client/problem/dto/response/ChildProblemsClientGetResponse.java

@@ -0,0 +1,19 @@
+package com.moplus.moplus_server.client.problem.dto.response;
+
+import com.moplus.moplus_server.domain.problem.domain.childProblem.ChildProblem;
+import com.moplus.moplus_server.domain.problem.domain.problem.Problem;
+import java.util.List;
+import lombok.Builder;
+
+@Builder
+public record ChildProblemsClientGetResponse(
+        String mainProblemImageUrl,
+        List<Long> childProblemIds
+) {
+    public static ChildProblemsClientGetResponse of(Problem problem) {
+        return ChildProblemsClientGetResponse.builder()
+                .mainProblemImageUrl(problem.getMainProblemImageUrl())
+                .childProblemIds(problem.getChildProblems().stream().map(ChildProblem::getId).toList())
+                .build();
+    }
+}

src/main/java/com/moplus/moplus_server/client/problem/service/ProblemsGetService.java

@@ -4,6 +4,7 @@
 import com.moplus.moplus_server.admin.publish.domain.Publish;
 import com.moplus.moplus_server.client.problem.dto.response.AllProblemGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ChildProblemClientGetResponse;
+import com.moplus.moplus_server.client.problem.dto.response.ChildProblemsClientGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ProblemClientGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ProblemFeedProgressesGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ProblemClientThumbnailResponse;
@@ -235,4 +236,25 @@ public ProblemClientThumbnailResponse getProblemThumbnail(Long publishId, Long p
         Problem problem = problemRepository.findByIdElseThrow(problemId);
         return ProblemClientThumbnailResponse.of(problemNumber + 1, problem);
     }
+
+    @Transactional(readOnly = true)
+    public ChildProblemsClientGetResponse getChildProblems(Long publishId, Long problemId) {
+        // 발행 조회
+        Publish publish = publishRepository.findByIdElseThrow(publishId);
+        denyAccessToFuturePublish(publish);
+
+        // 문항 세트 조회
+        ProblemSet problemSet = problemSetRepository.findByIdElseThrow(publish.getProblemSetId());
+        List<Long> problemIds = problemSet.getProblemIds();
+
+        // 발행된 문항세트에 포함된 문항인지 검사
+        int problemNumber = problemIds.indexOf(problemId);
+        if (problemNumber == -1) {
+            throw new NotFoundException(ErrorCode.PROBLEM_NOT_FOUND_IN_PROBLEM_SET);
+        }
+
+        //문항 조회
+        Problem problem = problemRepository.findByIdElseThrow(problemId);
+        return ChildProblemsClientGetResponse.of(problem);
+    }
 }