댓글/대댓글 작성, 조회 API

src/main/java/com/catcher/app/AppApplication.java

@@ -2,10 +2,14 @@
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.autoconfigure.domain.EntityScan;
 import org.springframework.context.annotation.ComponentScan;
+import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
 
 @SpringBootApplication
 @ComponentScan(basePackages = {"com.catcher.core", "com.catcher.resource"})
+@EnableJpaRepositories(basePackages = {"com.catcher.datasource"})
+@EntityScan(basePackages = {"com.catcher.core.domain.entity"})
 public class AppApplication {
 
 	public static void main(String[] args) {

src/main/java/com/catcher/core/domain/command/Command.java

@@ -1,4 +1,5 @@
 package com.catcher.core.domain.command;
 
-public interface Command {
+public interface Command<T> {
+    T execute();
 }

src/main/java/com/catcher/core/domain/command/CommandExecutor.java

@@ -0,0 +1,5 @@
+package com.catcher.core.domain.command;
+
+public interface CommandExecutor {
+     <T> T run(Command<T> command);
+}

src/main/java/com/catcher/core/domain/command/CommentCommandExecutor.java

@@ -0,0 +1,13 @@
+package com.catcher.core.domain.command;
+
+import org.springframework.stereotype.Component;
+
+@Component
+public class CommentCommandExecutor implements CommandExecutor {
+
+    @Override
+    public <T> T run(Command<T> command) {
+        return command.execute();
+    }
+
+}

src/main/java/com/catcher/core/domain/command/GetCommentCommand.java

@@ -0,0 +1,19 @@
+package com.catcher.core.domain.command;
+
+import com.catcher.core.domain.entity.Comment;
+import com.catcher.core.service.CommentService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+
+@RequiredArgsConstructor
+public class GetCommentCommand implements Command<Page<Comment>> {
+
+    private final CommentService commentService;
+
+    private final Pageable pageable;
+    @Override
+    public Page<Comment> execute() {
+        return commentService.findByParentIsNull(pageable);
+    }
+}

src/main/java/com/catcher/core/domain/command/PostCommentCommand.java

@@ -0,0 +1,21 @@
+package com.catcher.core.domain.command;
+
+import com.catcher.core.domain.request.PostCommentRequest;
+import com.catcher.core.service.CommentService;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+public class PostCommentCommand implements Command<Void> {
+
+    private final CommentService commentService;
+
+    private final PostCommentRequest postCommentRequest;
+
+    @Override
+    public Void execute() {
+        commentService.saveSingleComment(postCommentRequest.getUserId(), postCommentRequest.getContents());
+
+        return null;
+    }
+
+}

src/main/java/com/catcher/core/domain/command/PostCommentReplyCommand.java

@@ -0,0 +1,25 @@
+package com.catcher.core.domain.command;
+
+import com.catcher.core.domain.request.PostCommentReplyRequest;
+import com.catcher.core.service.CommentService;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+public class PostCommentReplyCommand implements Command<Void> {
+
+    private final CommentService commentService;
+
+    private final PostCommentReplyRequest postCommentReplyRequest;
+
+    @Override
+    public Void execute() {
+        commentService.saveSingleReply(
+                postCommentReplyRequest.getParentId(),
+                postCommentReplyRequest.getUserId(),
+                postCommentReplyRequest.getContents()
+        );
+
+        return null;
+    }
+
+}

src/main/java/com/catcher/core/domain/entity/Comment.java

@@ -0,0 +1,33 @@
+package com.catcher.core.domain.entity;
+
+import jakarta.persistence.*;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@Entity
+@Getter
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class Comment {
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @ManyToOne
+    @JoinColumn(name = "parent_id")
+    private Comment parent;
+
+    @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
+    @Builder.Default
+    private List<Comment> replies = new ArrayList<>();
+
+    private Long userId;
+
+    private String contents;
+}

src/main/java/com/catcher/core/domain/request/PostCommentReplyRequest.java

@@ -0,0 +1,19 @@
+package com.catcher.core.domain.request;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Getter
+@Builder // TODO: 테스트를 위해서만 필요한 경우?
+@NoArgsConstructor
+@AllArgsConstructor
+public class PostCommentReplyRequest {
+
+    private Long userId;
+
+    private Long parentId;
+
+    private String contents;
+}

src/main/java/com/catcher/core/domain/request/PostCommentRequest.java

@@ -0,0 +1,17 @@
+package com.catcher.core.domain.request;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Getter
+@Builder // TODO: 테스트를 위해서만 필요한 경우?
+@NoArgsConstructor
+@AllArgsConstructor
+public class PostCommentRequest {
+
+    private Long userId;
+
+    private String contents;
+}

src/main/java/com/catcher/core/domain/response/GetCommentsByPageResponse.java

@@ -0,0 +1,43 @@
+package com.catcher.core.domain.response;
+
+import com.catcher.core.domain.entity.Comment;
+import lombok.Builder;
+import lombok.Getter;
+import org.springframework.data.domain.Page;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Getter
+@Builder
+public class GetCommentsByPageResponse {
+
+    private Long id;
+
+    private String contents;
+
+    private List<GetCommentsByPageResponse> childComments;
+
+    public static List<GetCommentsByPageResponse> createGetCommentsByPageResponseList(Page<Comment> commentPage) {
+        return commentPage
+                .stream()
+                .map(GetCommentsByPageResponse::buildRecursiveCommentResponse)
+                .collect(Collectors.toList());
+    }
+
+    private static GetCommentsByPageResponse buildRecursiveCommentResponse(Comment comment) {
+        GetCommentsByPageResponse response = GetCommentsByPageResponse
+                .builder()
+                .id(comment.getId())
+                .contents(comment.getContents())
+                .childComments(new ArrayList<>())
+                .build();
+
+        for (Comment reply : comment.getReplies()) {
+            response.getChildComments().add(buildRecursiveCommentResponse(reply));
+        }
+
+        return response;
+    }
+}

src/main/java/com/catcher/core/service/CommentService.java

@@ -0,0 +1,48 @@
+package com.catcher.core.service;
+
+import com.catcher.core.domain.entity.Comment;
+import com.catcher.datasource.CommentRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@RequiredArgsConstructor
+public class CommentService {
+
+    private final CommentRepository commentRepository;
+
+    @Transactional
+    public Page<Comment> findByParentIsNull(final Pageable pageable) {
+        return commentRepository.findByParentIsNull(pageable);
+    }
+
+    @Transactional
+    public Comment saveSingleComment(final Long userId, final String contents) {
+        return commentRepository.save(Comment
+                .builder()
+                .userId(userId)
+                .contents(contents)
+                .build());
+    }
+
+    @Transactional
+    public Comment saveSingleReply(Long parentId, Long userId, String contents) {
+        final Comment parentComment = commentRepository
+                .findById(parentId)
+                .orElseThrow(); //TODO: fill custom exception
+
+        final Comment reply = Comment
+                .builder()
+                .userId(userId)
+                .parent(parentComment)
+                .contents(contents)
+                .build();
+
+        parentComment.getReplies().add(reply);
+
+        return reply;
+    }
+}

src/main/java/com/catcher/datasource/CommentRepository.java

@@ -0,0 +1,14 @@
+package com.catcher.datasource;
+
+import com.catcher.core.domain.entity.Comment;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface CommentRepository extends JpaRepository<Comment, Long> {
+
+    // TODO: N+1 join
+//    @Query(value = "SELECT DISTINCT c FROM Comment c LEFT OUTER JOIN FETCH c.replies WHERE c.parent IS NULL")
+    Page<Comment> findByParentIsNull(Pageable pageable);
+
+}

src/main/java/com/catcher/resource/CommentAPiController.java

@@ -0,0 +1,45 @@
+package com.catcher.resource;
+
+import com.catcher.core.domain.command.*;
+import com.catcher.core.domain.entity.Comment;
+import com.catcher.core.domain.request.PostCommentReplyRequest;
+import com.catcher.core.domain.request.PostCommentRequest;
+import com.catcher.core.domain.response.GetCommentsByPageResponse;
+import com.catcher.core.service.CommentService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.web.PageableDefault;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@RequiredArgsConstructor
+@RestController
+@RequestMapping("/comment")
+public class CommentAPiController {
+
+    private final CommentService commentService;
+
+    private final CommentCommandExecutor commandExecutor;
+
+    @PostMapping
+    public void postComment(@RequestBody PostCommentRequest postCommentRequest) {
+        Command<Void> command = new PostCommentCommand(commentService, postCommentRequest);
+        commandExecutor.run(command);
+    }
+
+    @PostMapping("/reply")
+    public void replyComment(@RequestBody PostCommentReplyRequest postCommentReplyRequest) {
+        Command<Void> command = new PostCommentReplyCommand(commentService, postCommentReplyRequest);
+        commandExecutor.run(command);
+    }
+
+    @GetMapping
+    public List<GetCommentsByPageResponse> getComments(@PageableDefault(size = 20, sort = {"id"}) Pageable pageable) {
+        Command<Page<Comment>> command = new GetCommentCommand(commentService, pageable);
+        Page<Comment> commentPage = commandExecutor.run(command);
+
+        return GetCommentsByPageResponse.createGetCommentsByPageResponseList(commentPage);
+    }
+}

src/test/java/com/catcher/app/AppApplicationTests.java

@@ -1,11 +1,15 @@
 package com.catcher.app;
 
 import org.junit.jupiter.api.Test;
+import org.springframework.boot.autoconfigure.domain.EntityScan;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.context.annotation.ComponentScan;
+import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
 
 @SpringBootTest
 @ComponentScan(basePackages = {"com.catcher.resource"})
+@EnableJpaRepositories(basePackages = {"com.catcher.datasource"})
+@EntityScan(basePackages = {"com.catcher.core.domain.entity"})
 class AppApplicationTests {
 
 	@Test

src/test/java/com/catcher/datasource/TestCommentRepository.java

@@ -0,0 +1,11 @@
+package com.catcher.datasource;
+
+import com.catcher.core.domain.entity.Comment;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+// TODO: 프로덕션 코드에는 없는 기능이 필요한 경우?
+public interface TestCommentRepository extends JpaRepository<Comment, Long> {
+
+    Comment findFirstByUserIdAndContentsOrderByIdDesc(Long userId, String contents);
+
+}