[22] 항해99 주특기 숙련주차 시험 Spring

2022. 12. 8. 13:03

STEP 1 (다대일 단방향)

책 : 서점 = N : 1 이라고 가정하고 제출한 답안

package com.example.spring_week_2_test.entity;

import com.example.spring_week_2_test.dto.BookRequestDto;
import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

@Entity
@Getter
@NoArgsConstructor
@Table(name = "Book") //테이블명 선언
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "book_id") //PK설정
    private Long id;

    @Column(nullable = false)
    private String author;

    @Column(nullable = false)
    private String name;

    @Column(nullable = false)
    private int price;

    @Column(nullable = false)
    private Long quantity;

    @ManyToOne
    @JoinColumn(name = "book_store_id", nullable = false)
    private BookStore bookStore; //FK는 book_store_id 가 된다.


}

package com.example.spring_week_2_test.entity;

import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

@Entity
@Getter
@NoArgsConstructor
@Table(name = "BookStore")
public class BookStore {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "book_store_id")
    private Long id;

    @Column(nullable = false)
    private String location;

    @Column(nullable = false)
    private String name;
}

STEP2 ( 다대일 양방향 )

책 : 서점 = N : 1 이라고 가정하고 제출한 답안

package com.example.spring_week_2_test.entity;

import com.example.spring_week_2_test.dto.BookRequestDto;
import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

@Entity
@Getter
@NoArgsConstructor
@Table(name = "Book")
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "book_id")
    private Long id;

    @Column(nullable = false)
    private String author;

    @Column(nullable = false)
    private String name;

    @Column(nullable = false)
    private int price;

    @Column(nullable = false)
    private Long quantity;

    @ManyToOne
    @JoinColumn(name = "book_store_id", nullable = false)
    private BookStore bookStore;

}

package com.example.spring_week_2_test.entity;

import com.example.spring_week_2_test.dto.BookStoreRequestDto;
import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import java.util.ArrayList;
import java.util.List;

@Entity
@Getter
@NoArgsConstructor
@Table(name = "BookStore")
public class BookStore {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "book_store_id")
    private Long id;

    @Column(nullable = false)
    private String location;

    @Column(nullable = false)
    private String name;

    @OneToMany(mappedBy = "bookStore")
    private List<Book> bookList = new ArrayList<>();

}

STEP3. 일대다 단방향 연관관계

책 : 회원 = N : 1 이라고 가정하고 제출한 답안

package com.example.spring_week_2_test.entity;

import com.example.spring_week_2_test.dto.BookStoreRequestDto;
import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import java.util.ArrayList;
import java.util.List;

@Entity
@Getter
@NoArgsConstructor
@Table(name = "BookStore")
public class BookStore {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "book_store_id")
    private Long id;

    @Column(nullable = false)
    private String location;

    @Column(nullable = false)
    private String name;

    @OneToMany(mappedBy = "bookStore")
    private List<Book> bookList = new ArrayList<>();

    @OneToMany
    @JoinColumn(name = "book_store_id")
    private List<Member> memberList = new ArrayList<>();

}

package com.example.spring_week_2_test.entity;

import jakarta.persistence.*;

@Entity
@Getter
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "Member")
public class Member {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "member_id")
    private Long id;

    @Column(nullable = false)
    private String address;

    @Column(nullable = false)
    private String email;

    @Column(nullable = false)
    private String nickname;

    @Column(nullable = false)
    private String password;

    @Column(nullable = false)
    private String phoneNumber;
}

STEP4. 구매(Purchase) Entity를 사용해서 (Member)과 책(Book)의 연관관계를 맺어보세요!

구매 : 회원 = N : 1

구매 : 책 = N : 1

이라고 가정하여 작성한 답안.

구매와 책 관계가 헷갈렸는데, 코드를 생각해보면 해당 책에 대한 코드는 하나일 것이고, 그 책에 대한 구매가 여러번 발생할 것으로 생각하면 이해가 조금 쉽다 !

package com.example.spring_week_2_test.entity;

import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;

import java.util.ArrayList;
import java.util.List;

@Entity
@Getter
@NoArgsConstructor
@Table(name = "Purchase")
public class Purchase {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "purchase_id")
    private Long id;

    @ManyToOne
    @JoinColumn(name = "member_id")
    private Member member;

    @ManyToOne
    @JoinColumn(name = "book_id")
    private Book book;

}

package com.example.spring_week_2_test.entity;

import com.example.spring_week_2_test.dto.BookRequestDto;
import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import java.util.ArrayList;
import java.util.List;

@Entity
@Getter
@NoArgsConstructor
@Table(name = "Book")
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "book_id")
    private Long id;

    @Column(nullable = false)
    private String author;

    @Column(nullable = false)
    private String name;

    @Column(nullable = false)
    private int price;

    @Column(nullable = false)
    private long quantity;

    @ManyToOne
    @JoinColumn(name = "book_store_id", nullable = false)
    private BookStore bookStore;

    @OneToMany(mappedBy = "book")
    private List<Purchase> purchases = new ArrayList<>();
}

package com.example.spring_week_2_test.entity;

import jakarta.persistence.*;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;

import java.util.ArrayList;
import java.util.List;

@Entity
@Getter
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "Member")
public class Member {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "member_id")
    private Long id;

    @Column(nullable = false)
    private String address;

    @Column(nullable = false)
    private String email;

    @Column(nullable = false)
    private String nickname;

    @Column(nullable = false)
    private String password;

    @Column(nullable = false)
    private String phoneNumber;

    @OneToMany(mappedBy = "member")
    private List<Purchase> purchaseList = new ArrayList<>();

}

스텝 4 까지 했을 때 ERD

틀린 부분

1. Book Entity의 quantity 타입을 long 으로 했어야 하는데 Long 으로 작성했다.

2. STEP4 Purchase 부분 지연로딩 (fetch = FetchType.LAZY) 추가

package com.example.spring_week_2_test.entity;

import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;

import java.util.ArrayList;
import java.util.List;

@Entity
@Getter
@NoArgsConstructor
@Table(name = "Purchase")
public class Purchase {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "purchase_id")
    private Long id;

    @ManyToOne(fetch = FetchType.LAZY) //(fetch = FetchType.LAZY) 추가
    @JoinColumn(name = "member_id") 
    private Member member;

    @ManyToOne(fetch = FetchType.LAZY) //(fetch = FetchType.LAZY) 추가
    @JoinColumn(name = "book_id") 
    private Book book;

}

참고 자료 :

[JPA] 다양한 연관관계 매핑 (1) 다대일, 일대다

엔티티의 연관관계를 매핑할 때는 3가지를 고려해야한다. 다중성 단방향, 양방향 연관관계의 주인 먼저 두 엔티티가 일대일 관계일지 일대다 관계인지 다중성을 고려한다. 다음으로, 두 엔티티

jgrammer.tistory.com

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