JPA：关系的目标是否有可能成为非实体？

Question

以下代码在Kotlin中。

我有一个TestExecutionSummary实体

@Entity
class TestExecutionSummary : Serializable {
    @EmbeddedId
    lateinit var id: TestExecutionId
    ...
    @OneToMany(cascade = [CascadeType.ALL], mappedBy = "testExecutionSummary")
    var failures: List<TestFailure> = mutableListOf()     
}
@Embeddable
data class TestExecutionId(
        var stepExecutionId: Long,
        var jobExecutionId: Long
) : Serializable

和一个TestFailure实体

@Entity
class TestFailure : Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    var id: Long? = null
    @Column(length = 999)
    lateinit var testId: String
    @JoinColumns(
            JoinColumn(name = "stepExecutionId", referencedColumnName = "stepExecutionId"),
            JoinColumn(name = "jobExecutionId", referencedColumnName = "jobExecutionId")
    )
    @ManyToOne
    lateinit var testExecutionSummary: TestExecutionSummary
    @Column(length = 999)
    var message: String? = null
}

这很好用，但令我TestFailure是TestFailure没有独立存在，并且实际上没有资格作为实体IMO。 是否可以在不使TestFailure成为实体的情况下保持所示的关系？

Answer 1

JPA 2.0具有ElementCollection ，这正是我想要的。

@ElementCollection(fetch = FetchType.EAGER)
@CollectionTable(
        name = "TEST_FAILURE",
        joinColumns = [
            JoinColumn(name = "stepExecutionId", referencedColumnName = "stepExecutionId"),
            JoinColumn(name = "jobExecutionId", referencedColumnName = "jobExecutionId")
        ]
)
var failures: List<TestFailure> = mutableListOf()

@Embeddable
class TestFailure : Serializable {
    @Column(length = 999)
    lateinit var testId: String
    @Column(length = 999)
    var message: String? = null
}

Answer 2

您要求使用@Embeddable，但不适用于@OneToMany。 解决方法，请参阅在JPA中将单个表映射到可嵌入集合。