Question

我试图在订单和订单产品之间实现一对多关联，但我总是遇到此异常：

Foreign key (FKmn6eaqdlnl33lnryjkwu09r0m:order_product_entity [order_id,product_id])) must have same number of columns as the referenced primary key (orders [id])

我知道这意味着什么，但是我不确定应该如何更改方案来解决它。我的设计基于本教程：Spring Java eCommerce Tutorial

除了我的代码是用Kotlin编写的，我无法分辨出差异。

我正在将Spring Boot与Spring Data JPA和Kotlin一起使用。

我的产品实体：

@Entity
@Table(name = "product")
data class ProductEntity(
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        var id: Long,
        @NotNull(message = "Product name is required")
        var name: String,
        var price: Double,
        var description: String

)

我的订单实体：

@Entity
@Table(name = "orders")
data class OrderEntity(
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        var id:Long,

        var dateCreated:Date,

        var status:String,

        @JsonManagedReference
        @OneToMany(cascade = arrayOf(CascadeType.ALL), mappedBy = "orderProductEntityId")
        @Valid
        val orderProducts: List<OrderProductEntity>
)

OrderProductEntity：

@Entity
data class OrderProductEntity(
        @EmbeddedId
        @JsonIgnore
        var orderProductEntityId: OrderProductEntityId,

        @JsonBackReference
        @ManyToOne(optional = false, fetch = FetchType.LAZY)
        var order: OrderEntity,

        @ManyToOne(optional = false, fetch = FetchType.LAZY)
        var product: ProductEntity,

        @Column(nullable = false)
        var quantity: Int = 0
)

我的复合主键：

@Embeddable
data class OrderProductEntityId(
        @Column(name = "order_id")
        var orderId: Long = 0,

        @Column(name = "product_id")
        var productId: Long = 0
) : Serializable

有什么建议吗？

Answer 1

我相信您使用的是“派生身份”。尝试像这样映射<div class="profile_gallery_image"><img class="myImg" src='https://via.placeholder.com/150' height="100%" width="100%" /></div> <div class="profile_gallery_image"><img class="myImg" src='https://via.placeholder.com/150' height="100%" width="100%" /></div> <div class="profile_gallery_image"><img class="myImg" src='https://via.placeholder.com/150' height="100%" width="100%" /></div> <div class="profile_gallery_image"><img class="myImg" src='https://via.placeholder.com/150' height="100%" width="100%" /></div> <div class="profile_gallery_image"><img class="myImg" src='https://via.placeholder.com/150' height="100%" width="100%" /></div> <div class="profile_gallery_image"><img class="myImg" src='https://via.placeholder.com/150' height="100%" width="100%" /></div>  <div id="myModal" class="modal"> <span class="close">×</span> <img class="modal-content" id="img01"> </div>：

OrderProductEntity

请注意新的@Entity data class OrderProductEntity( @EmbeddedId @JsonIgnore var orderProductEntityId: OrderProductEntityId, @JsonBackReference @ManyToOne(optional = false, fetch = FetchType.LAZY) @MapsId("orderId") // maps orderId attribute of embedded id var order: OrderEntity, @ManyToOne(optional = false, fetch = FetchType.LAZY) @MapsId("productId") // maps productId attribute of embedded id var product: ProductEntity, @Column(nullable = false) var quantity: Int = 0 )批注。

在JPA 2.2 spec的第2.4.1节中讨论了派生的身份（带有示例）。

一对多外键的列数必须与引用的主键相同

1 个答案: