기초 프로젝트: 뉴스 피드 앱 만들기

팀 노션 링크

개발 환경

1. 프로젝트 기간: 2025.02.14 - 2025.02.20
2. 사용 기술: JAVA, SpringBoot, JPA, Spring Data JPA, MySQL

역할 분담

🦦 juno-soodal : user crud, 인증/인가, 공통 로직 처리, comment like

🤡 mmj-159 : bookmark

👻 SuhyeonB : post crud, post like

🍊 euuns : comment crud, friend, friend-apply

목차

1. API 및 기능 명세서
2. ERD 작성
3. SQL 작성
4. 트러블 슈팅
5. 예외 처리

설계

API 및 기능 명세서

👤 Users

📑 Posts

🏷️ Comments

👥 Friends

🔖 Bookmarks

🔐 인증/인가: Session

🚨 400 Bad Request: 잘못된 접근(비밀번호, 이메일 등 형식)
　 401 Unauthorized: 유효한 인증 자격이 없음 (로그인)
　 403 Forbidden: 엑세스 권한 없음 (세션)
　 404 Not Found: 찾을 수 없는 접근(요청 id)

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ERD

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SQL

👤 User

CREATE TABLE user (
    id BIGINT NOT NULL AUTO_INCREMENT,
    name VARCHAR(255) NOT NULL,
    email VARCHAR(255) NOT NULL UNIQUE,
    password VARCHAR(255) NOT NULL,
    interest_tag VARCHAR(255) NOT NULL,
    status VARCHAR(50) DEFAULT 'ACTIVE',
    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    PRIMARY KEY (id)
);

📄 post

CREATE TABLE post (
    id BIGINT NOT NULL AUTO_INCREMENT,
    user_id BIGINT NOT NULL,
    title VARCHAR(255) NOT NULL,
    contents LONGTEXT NOT NULL,
    keyword VARCHAR(255),
    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    PRIMARY KEY (id),
    CONSTRAINT fk_post_user FOREIGN KEY (user_id) REFERENCES user(id)
);

❤ post_like

CREATE TABLE post_like (
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    post_id BIGINT NOT NULL,
    user_id BIGINT NOT NULL,
    CONSTRAINT unique_post_user UNIQUE (post_id, user_id),
    CONSTRAINT fk_post_like_post FOREIGN KEY (post_id) REFERENCES post(id) ON DELETE CASCADE,
    CONSTRAINT fk_post_like_user FOREIGN KEY (user_id) REFERENCES user(id) ON DELETE CASCADE
);

📑 Comment

CREATE TABLE comment (
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    user_id BIGINT NOT NULL,
    post_id BIGINT NOT NULL,
    contents TEXT NOT NULL,
    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    CONSTRAINT fk_comment_user FOREIGN KEY (user_id) REFERENCES user(id) ON DELETE CASCADE,
    CONSTRAINT fk_comment_post FOREIGN KEY (post_id) REFERENCES post(id) ON DELETE CASCADE
);

💙 Comment_like

CREATE TABLE comment_like (
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    user_id BIGINT NOT NULL,
    comment_id BIGINT NOT NULL,
    CONSTRAINT unique_comment_user UNIQUE (user_id, comment_id),
    CONSTRAINT fk_comment_like_user FOREIGN KEY (user_id) REFERENCES user(id) ON DELETE CASCADE,
    CONSTRAINT fk_comment_like_comment FOREIGN KEY (comment_id) REFERENCES comment(id) ON DELETE CASCADE
);

💌 apply

CREATE TABLE apply (
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    sender_id BIGINT NOT NULL,
    receiver_id BIGINT NOT NULL,
    CONSTRAINT friend_apply UNIQUE (sender_id, receiver_id),
    CONSTRAINT fk_apply_sender FOREIGN KEY (sender_id) REFERENCES user(id) ON DELETE CASCADE,
    CONSTRAINT fk_apply_receiver FOREIGN KEY (receiver_id) REFERENCES user(id) ON DELETE CASCADE
);

👥 Friends

CREATE TABLE friend (
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    to_user_id BIGINT NOT NULL,
    from_user_id BIGINT NOT NULL,
    CONSTRAINT unique_friend UNIQUE (to_user_id, from_user_id),
    CONSTRAINT fk_friend_to_user FOREIGN KEY (to_user_id) REFERENCES user(id) ON DELETE CASCADE,
    CONSTRAINT fk_friend_from_user FOREIGN KEY (from_user_id) REFERENCES user(id) ON DELETE CASCADE
);

🔖 Bookmarks

CREATE TABLE bookmark (
    bookmark_id BIGINT AUTO_INCREMENT PRIMARY KEY,
    bookmark_user_id BIGINT NOT NULL,
    bookmark_post_id BIGINT NOT NULL,
    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    CONSTRAINT fk_bookmark_user FOREIGN KEY (bookmark_user_id) REFERENCES user(id) ON DELETE CASCADE,
    CONSTRAINT fk_bookmark_post FOREIGN KEY (bookmark_post_id) REFERENCES post(id) ON DELETE CASCADE
);

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troubleshooting

🔎 상황

댓글 목록 조회 시 작성자(User)와 게시글 제목(Post) 정보를 함께 반환.
Comment entity에서 User와 Post를 @ManyToOne(fetch = FetchType.LAZY)로 설정.
CommentResponseDto에서 getUser().getName() 또는 getPost().getTitle()을 호출하면 추가 쿼리가 발생

💥 N+1 문제 발생

1개 쿼리 후 추가적으로 N개의 쿼리가 발생하는 비효율적인 데이터 조회 문제

🚀 JOIN FETCH 활용으로 해결

✅ JOIN FETCH가 적용된 후,

findCommentsWithPostAndUserByPostId() 실행 시
Comment 엔티티를 조회하면서 즉시 User와 Post 객체를 함께 호출

따라서 proxy 객체가 아니라 실제 entity 로드
추가적인 LazyInitializationException 없이 getUser().getName() 안전하게 호출 가능

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exception

🎯 common/exception/ErrorCode.java

※ 모든 예외가 아닌 일부 예외 작성