JPA：外键，只有一个来自复合键答案

【问题标题】：JPA: Foreign key which only one from composite keyJPA：外键，只有一个来自复合键
【发布时间】：2021-07-23 10:39:09
【问题描述】：

我无法让复合主键和外键在 JPA 2/Hibernate 中工作。我正在尝试用 A 和 B 创建一个简单的场景：

CREATE TABLE Customer(
    customer_id uuid,
    employee_id int,
    created_at timestamp with time zone DEFAULT now(),
    
    CONSTRAINT customer_id_employee_id_pkey PRIMARY KEY (customer_id, employee_id),
    CONSTRAINT fk_owner_owner_id FOREIGN KEY (customer_id)
        REFERENCES public.owner (id) MATCH SIMPLE
        ON UPDATE CASCADE
        ON DELETE CASCADE
)

我应该如何创建实体类？

我在下面尝试过

@EqualsAndHashCode
@Data
public class CustomerId implements Serializable {
    private UUID customerId;
    private Long employeeId;
}


@Data
@Entity
@IdClass(CustomerId.class)
@Table(name = "customer")
public class Customer implements Serializable {
    private static final long serialVersionUID = -234295442215152987L;

    @Id
    @Column(name = "customer_id")
    private UUID customerId;

    @Id
    @Column(name = "employee_id")
    private Long employeeId;

    @CreationTimestamp
    @Column(name = "created_at", insertable = false, updatable = false)
    private OffsetDateTime createdAt;
}

但我不确定应该在哪个类中映射作为外键的 customer_id。请帮帮我

【问题讨论】：

标签： jpa orm composite-key

【解决方案1】：

它应该这样工作

@Data
@Embeddable
public class CustomerId implements Serializable {
    private UUID customerId;
    private Long employeeId;
}


@Data
@Entity
@Table(name = "customer")
public class Customer implements Serializable {
    private static final long serialVersionUID = -234295442215152987L;

    @EmbeddedId
    @Column(name = "customer_id")
    private CustomerId customerId;


    @CreationTimestamp
    @Column(name = "created_at", insertable = false, updatable = false)
    private OffsetDateTime createdAt;
}

【讨论】：