JPA：关系的目标是否有可能成为非实体？

Question

The following code is in Kotlin.

I've a TestExecutionSummary entity

@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

and a TestFailure entity

@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
}

This works fine, but what's bugging me is that TestFailure has no independent existence, and doesn't really qualify as an entity IMO. Is it possible to maintain the shown relationship without making TestFailure an entity?

Answer 1

JPA 2.0 has ElementCollection which is exactly what I'm looking for.

@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

You are asking for @Embeddable but it is not available for @OneToMany. See Mapping Single Table to Embeddable Collection in JPA for workaround