주변 코스 조회 API에 페이징 적용 (#452)

* feat: 주변 코스 조회 API에 페이징 기능 추가

* fix: Course가 Spring Data MongoDB에 의해 제대로 매핑되지 않는 문제를 Converter로 해결

- MongoTemplate을 사용하는 방식도 고려했으나, 이보단 Converter만 구현하는 것이 편하다고 느낌
- 추후에 schemaVersion이 추가되었을 때에도 유연하게 대응 가능

* refactor: 생성되면 안되는 Converter 클래스를 abstract로 변경

* test: RepositoryTest를 가독성 좋게 setUp 절로 분리

* fix: PageNumber가 null 이거나 음수인 경우에 대응

* fix: Id가 세팅되어 있는 경우(업데이트)에는 DB 저장시 Id를 정상적으로 세팅

* chore: 불필요한 Converter 등록 제거

* refactor: 등록되지 않는 converter들은 내부 클래스로 갖도록 리팩터링

* test: 페이징 테스트를 다양하게 추가

Author: dompoo

backend/src/main/java/coursepick/coursepick/application/CourseApplicationService.java

@@ -7,6 +7,9 @@
 import coursepick.coursepick.domain.Meter;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -23,11 +26,12 @@ public class CourseApplicationService {
     private final WalkingRouteService walkingRouteService;
 
     @Transactional(readOnly = true)
-    public List<CourseResponse> findNearbyCourses(double mapLatitude, double mapLongitude, Double userLatitude, Double userLongitude, int scope) {
+    public List<CourseResponse> findNearbyCourses(double mapLatitude, double mapLongitude, Double userLatitude, Double userLongitude, int scope, Integer pageNumber) {
         final Coordinate mapPosition = new Coordinate(mapLatitude, mapLongitude);
-        Meter meter = new Meter(scope).clamp(1000, 3000);
+        final Meter meter = new Meter(scope).clamp(1000, 3000);
+        Pageable pageable = createPageable(pageNumber);
 
-        List<Course> coursesWithinScope = courseRepository.findAllHasDistanceWithin(mapPosition, meter);
+        Slice<Course> coursesWithinScope = courseRepository.findAllHasDistanceWithin(mapPosition, meter, pageable);
 
         if (userLatitude == null || userLongitude == null) {
             return coursesWithinScope
@@ -43,6 +47,11 @@ public List<CourseResponse> findNearbyCourses(double mapLatitude, double mapLong
                 .toList();
     }
 
+    private static Pageable createPageable(Integer pageNumber) {
+        if (pageNumber == null || pageNumber < 0) return PageRequest.of(0, 10);
+        else return PageRequest.of(pageNumber, 10);
+    }
+
     @Transactional(readOnly = true)
     public Coordinate findClosestCoordinate(String id, double latitude, double longitude) {
         Course course = courseRepository.findById(id)

backend/src/main/java/coursepick/coursepick/domain/Course.java

@@ -14,7 +14,7 @@
 import java.util.List;
 
 @Document
-@AllArgsConstructor(access = AccessLevel.PROTECTED, onConstructor_ = @PersistenceCreator)
+@AllArgsConstructor(access = AccessLevel.PUBLIC, onConstructor_ = @PersistenceCreator)
 @Getter
 @Accessors(fluent = true)
 public class Course {

backend/src/main/java/coursepick/coursepick/domain/CourseRepository.java

@@ -1,13 +1,16 @@
 package coursepick.coursepick.domain;
 
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
+
 import java.util.List;
 import java.util.Optional;
 
 public interface CourseRepository {
 
     void saveAll(Iterable<? extends Course> courses);
 
-    List<Course> findAllHasDistanceWithin(Coordinate target, Meter distance);
+    Slice<Course> findAllHasDistanceWithin(Coordinate target, Meter distance, Pageable pageable);
 
     List<Course> findByIdIn(List<String> ids);
 

backend/src/main/java/coursepick/coursepick/infrastructure/CourseRepositoryMongoTemplateImpl.java

@@ -2,7 +2,10 @@
 
 import coursepick.coursepick.domain.*;
 import lombok.RequiredArgsConstructor;
-import org.springframework.data.geo.Point;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
+import org.springframework.data.domain.SliceImpl;
 import org.springframework.data.mongodb.core.MongoTemplate;
 import org.springframework.data.mongodb.core.geo.GeoJsonPoint;
 import org.springframework.data.mongodb.core.query.Criteria;
@@ -30,23 +33,41 @@ public void saveAll(Iterable<? extends Course> courses) {
          */
         List<? extends Course> listCourses = StreamSupport.stream(courses.spliterator(), false)
                 .toList();
+
         mongoTemplate.insertAll(listCourses);
     }
 
     @Override
-    public List<Course> findAllHasDistanceWithin(Coordinate target, Meter distance) {
-        if (target == null || distance == null) return List.of();
+    public Slice<Course> findAllHasDistanceWithin(Coordinate target, Meter distance, Pageable pageable) {
+        if (target == null || distance == null) return Page.empty(pageable);
 
-        Point center = new GeoJsonPoint(target.longitude(), target.latitude());
-        Query query = Query.query(Criteria.where("segments").near(center).maxDistance(distance.value()));
-        return mongoTemplate.find(query, Course.class);
+        Criteria criteria = Criteria.where("segments")
+                .near(new GeoJsonPoint(target.longitude(), target.latitude()))
+                .maxDistance(distance.value());
+
+        if (pageable == null) {
+            Query query = Query.query(criteria);
+
+            return new SliceImpl<>(mongoTemplate.find(query, Course.class));
+        }
+
+        Query query = Query.query(criteria)
+                .with(pageable)
+                .limit(pageable.getPageSize() + 1);
+
+        List<Course> result = mongoTemplate.find(query, Course.class);
+
+        boolean hasNext = result.size() > pageable.getPageSize();
+        if (hasNext) result.removeLast();
+        return new SliceImpl<>(result, pageable, hasNext);
     }
 
     @Override
     public List<Course> findByIdIn(List<String> ids) {
         if (ids == null || ids.isEmpty()) return List.of();
 
         Query query = Query.query(Criteria.where("_id").in(ids));
+
         return mongoTemplate.find(query, Course.class);
     }
 
@@ -62,6 +83,7 @@ public boolean existsByName(CourseName courseName) {
         if (courseName == null) return false;
 
         Query query = Query.query(Criteria.where("name").is(courseName.value()));
+
         return mongoTemplate.exists(query, Course.class);
     }
 }

…ture/converter/SegmentListConverter.java …structure/converter/CourseConverter.javabackend/src/main/java/coursepick/coursepick/infrastructure/converter/SegmentListConverter.java renamed to backend/src/main/java/coursepick/coursepick/infrastructure/converter/CourseConverter.java backend/src/main/java/coursepick/coursepick/infrastructure/converter/SegmentListConverter.java renamed to backend/src/main/java/coursepick/coursepick/infrastructure/converter/CourseConverter.java

@@ -1,12 +1,10 @@
 package coursepick.coursepick.infrastructure.converter;
 
-import coursepick.coursepick.domain.Coordinate;
-import coursepick.coursepick.domain.GeoLine;
-import coursepick.coursepick.domain.GeoLineBuilder;
-import coursepick.coursepick.domain.Segment;
+import coursepick.coursepick.domain.*;
 import coursepick.coursepick.logging.LogContent;
 import lombok.extern.slf4j.Slf4j;
 import org.bson.Document;
+import org.bson.types.ObjectId;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.data.convert.ReadingConverter;
 import org.springframework.data.convert.WritingConverter;
@@ -15,16 +13,52 @@
 import java.util.Collections;
 import java.util.List;
 
-@Slf4j
-public class SegmentListConverter {
+public abstract class CourseConverter {
+
+    private static final SegmentListReader SEGMENTS_READER = new SegmentListReader();
+    private static final SegmentListWriter SEGMENTS_WRITER = new SegmentListWriter();
+
+    @WritingConverter
+    public static class Writer implements Converter<Course, Document> {
+        @Override
+        public Document convert(Course source) {
+            Document document = new Document();
+            if (source.id() != null && !source.id().isBlank()) {
+                document.put("_id", new ObjectId(source.id()));
+            }
+            document.put("name", source.name().value());
+            document.put("road_type", source.roadType().name());
+            document.put("incline_summary", source.inclineSummary().name());
+            document.put("segments", SEGMENTS_WRITER.convert(source.segments()));
+            document.put("length", source.length().value());
+            document.put("difficulty", source.difficulty().name());
+            return document;
+        }
+    }
+
+    @ReadingConverter
+    public static class Reader implements Converter<Document, Course> {
+        @Override
+        public Course convert(Document source) {
+            return new Course(
+                    source.getObjectId("_id").toHexString(),
+                    new CourseName(source.getString("name")),
+                    RoadType.valueOf(source.getString("road_type")),
+                    InclineSummary.valueOf(source.getString("incline_summary")),
+                    SEGMENTS_READER.convert(source.get("segments", Document.class)),
+                    new Meter(source.getDouble("length")),
+                    Difficulty.valueOf(source.getString("difficulty"))
+            );
+        }
+    }
 
     @WritingConverter
-    public static class Writer implements Converter<List<Segment>, Document> {
+    private static class SegmentListWriter implements Converter<List<Segment>, Document> {
         @Override
         public Document convert(List<Segment> source) {
             if (source == null) return null;
             List<List<List<Double>>> segmentsData = source.stream()
-                    .map(Writer::parseSegment)
+                    .map(SegmentListWriter::parseSegment)
                     .toList();
 
             Document document = new Document();
@@ -47,16 +81,17 @@ private static List<List<Double>> parseSegment(Segment segment) {
         }
     }
 
+    @Slf4j
     @ReadingConverter
-    public static class Reader implements Converter<Document, List<Segment>> {
+    private static class SegmentListReader implements Converter<Document, List<Segment>> {
         @Override
         public List<Segment> convert(Document source) {
             try {
                 if (source == null) return null;
                 List<List<List<Double>>> segmentsData = (List<List<List<Double>>>) source.get("coordinates");
 
                 return segmentsData.stream()
-                        .map(Reader::parseSegment)
+                        .map(SegmentListReader::parseSegment)
                         .toList();
             } catch (Exception e) {
                 log.warn("[EXCEPTION] 세그먼트 파싱 중 예외 발생", LogContent.exception(source, e));

backend/src/main/java/coursepick/coursepick/infrastructure/converter/CourseNameConverter.java

@@ -12,12 +12,8 @@ public class MongoConfig {
     @Bean
     public MongoCustomConversions mongoCustomConversions() {
         return new MongoCustomConversions(List.of(
-                new SegmentListConverter.Reader(),
-                new SegmentListConverter.Writer(),
-                new CourseNameConverter.Reader(),
-                new CourseNameConverter.Writer(),
-                new MeterConverter.Reader(),
-                new MeterConverter.Writer()
+                new CourseConverter.Reader(),
+                new CourseConverter.Writer()
         ));
     }
 }

backend/src/main/java/coursepick/coursepick/infrastructure/converter/MeterConverter.java

@@ -40,9 +40,10 @@ public List<CourseWebResponse> findNearbyCourses(
             @RequestParam("mapLng") double mapLongitude,
             @RequestParam(value = "userLat", required = false) Double userLatitude,
             @RequestParam(value = "userLng", required = false) Double userLongitude,
-            @RequestParam("scope") int scope
+            @RequestParam("scope") int scope,
+            @RequestParam(value = "page", required = false) Integer page
     ) {
-        List<CourseResponse> responses = courseApplicationService.findNearbyCourses(mapLatitude, mapLongitude, userLatitude, userLongitude, scope);
+        List<CourseResponse> responses = courseApplicationService.findNearbyCourses(mapLatitude, mapLongitude, userLatitude, userLongitude, scope, page);
         return CourseWebResponse.from(responses);
     }
 

backend/src/main/java/coursepick/coursepick/infrastructure/converter/MongoConfig.java

@@ -38,7 +38,8 @@ List<CourseWebResponse> findNearbyCourses(
             @Parameter(example = "127.1040109", required = true) double mapLongitude,
             @Parameter(example = "38.5165004") Double userLatitude,
             @Parameter(example = "126.1040109") Double userLongitude,
-            @Parameter(example = "1000", required = true) int scope
+            @Parameter(example = "1000", required = true) int scope,
+            @Parameter(example = "1") Integer page
     );
 
     @Operation(summary = "좌표에서 가장 가까운 코스 위 좌표 조회")
@@ -92,7 +93,7 @@ List<CoordinateWebResponse> routeToCourse(
             @Parameter(example = "37.5165004", required = true) double latitude,
             @Parameter(example = "127.1040109", required = true) double longitude
     );
-    
+
     @Operation(summary = "즐겨찾기 코스 조회")
     @ApiResponse(responseCode = "200")
     List<CourseWebResponse> findFavoriteCourses(