在兩個實體中映射相同的列表並使用彈簧數據更新列表

Question

我有兩個實體Sell和Buy，每個實體都有一個列表Offer，如下所示。

我的疑問是如何映射這兩個實體在Offer。我是否必須爲每個人添加一個帶有@ManyToOne註釋的屬性？我目前的映射是否正確？

此外，當我向要約列表添加新元素時，如何使用Spring Data更新它？ 我正在使用存儲庫JpaRepository，但沒有找到更新或合併bean的方法。

賣實體：

@Entity 
public class Sell implements Serializable { 

    @Id 
    @GeneratedValue(generator = "sell_sequence", strategy = GenerationType.SEQUENCE) 
    @SequenceGenerator(name = "sell_sequence", sequenceName = "sell_sequence", allocationSize = 1) 
    private Long id; 

    // other fields... 

    @OneToMany(cascade = { CascadeType.REMOVE, CascadeType.MERGE, CascadeType.PERSIST }) 
    @JoinTable(name = "selloffer", 
     joinColumns = @JoinColumn(name = "sell_id", referencedColumnName = "id"), 
     inverseJoinColumns = @JoinColumn(name = "offer_id", referencedColumnName = "id")) 
    private List<Offer> offers = new ArrayList<>(); 

    // constructors, getters and setters... 
} 

購買實體：

@Entity 
public class Buy implements Serializable { 

    @Id 
    @GeneratedValue(generator = "buy_sequence", strategy = GenerationType.SEQUENCE) 
    @SequenceGenerator(name = "buy_sequence", sequenceName = "buy_sequence", allocationSize = 1) 
    private Long id; 

    // other fields... 

    @OneToMany(cascade = { CascadeType.REMOVE }) 
    @JoinTable(name = "buyoffer", 
     joinColumns = @JoinColumn(name = "buy_id", referencedColumnName = "id"), 
     inverseJoinColumns = @JoinColumn(name = "offer_id", referencedColumnName = "id")) 
    private List<Offer> offers; 

    // constructors, getters and setters... 
} 

及發售：

@Entity 
public class Offer implements Serializable { 

    @Id 
    @GeneratedValue(generator = "offer_sequence", strategy = GenerationType.SEQUENCE) 
    @SequenceGenerator(name = "offer_sequence", sequenceName = "offer_sequence", allocationSize = 1) 
    private Long id; 

    @Column(length = 500) 
    String description; 

    @ManyToOne(cascade = { CascadeType.PERSIST }) 
    @JoinColumn(name = "bidder_id", nullable = false) 
    User bidder; 
} 

Answer 1

雖然我猜測，你的關係應該是OneToOne（或者多對一全無連接表），沒有連接表，這似乎可以解決你的問題，只需檢查報價中的連接列即可類（不知道它們是否適合您的情況）

@Entity 
public class Sell implements Serializable { 

    @Id 
    @GeneratedValue(generator = "sell_sequence", strategy = GenerationType.SEQUENCE) 
    @SequenceGenerator(name = "sell_sequence", sequenceName = "sell_sequence", allocationSize = 1) 
    private Long id; 

    // other fields... 

    @OneToMany(cascade = { CascadeType.REMOVE, CascadeType.MERGE, CascadeType.PERSIST },mappedBy = "sell") 

    private List<Offer> offers = new ArrayList<>(); 

    // constructors, getters and setters... 
} 

@Entity 
public class Buy implements Serializable { 

    @Id 
    @GeneratedValue(generator = "buy_sequence", strategy = GenerationType.SEQUENCE) 
    @SequenceGenerator(name = "buy_sequence", sequenceName = "buy_sequence", allocationSize = 1) 
    private Long id; 

    // other fields... 

    @OneToMany(cascade = { CascadeType.REMOVE },mappedBy = "buy") 
    private List<Offer> offers; 

    // constructors, getters and setters... 
} 

@Entity 
public class Offer implements Serializable { 

    @Id 
    @GeneratedValue(generator = "offer_sequence", strategy = GenerationType.SEQUENCE) 
    @SequenceGenerator(name = "offer_sequence", sequenceName = "offer_sequence", allocationSize = 1) 
    private Long id; 

    @Column(length = 500) 
    String description; 

    @ManyToOne(cascade = { CascadeType.PERSIST }) 
    @JoinColumn(name = "bidder_id", nullable = false) 
    User bidder; 

    @ManyToOne 
    @JoinTable(name = "selloffer", 
     joinColumns = @JoinColumn(name = "offer_id", referencedColumnName = "id"), 
     inverseJoinColumns =@JoinColumn(name = "sell_id", referencedColumnName = "id")) 
    private Sell sell; 

    @ManyToOne 
    @JoinTable(name = "buyoffer", 
     joinColumns = @JoinColumn(name = "offer_id", referencedColumnName = "id"), 
     inverseJoinColumns = @JoinColumn(name = "buy_id", referencedColumnName = "id")) 
    private Buy buy; 
}