我想通过first_user和second_user将User映射到Relationship，以便可以跟踪他们的关系状态。也许有更好的方法，我会很乐意考虑任何有用的建议。
当我尝试坚持时，主要问题到来了。当我检查数据库，但表user_relationship无法正常工作时，该关系的“关系”端似乎工作正常。
所以问题基本上是为什么在用户工作中不保持关系不持久？
编辑：我看过该帖子，建议将其重复。在接受的答案中，Sym-sym指出了固定的关系并提供了示例。我已经研究了示例，但是在关系的OneToMany端看到的唯一区别是maptedBy属性。我不太确定要映射哪一个，因为在关系的另一端有两个ManyToOne。我们将通过firstParty还是也许secondParty进行映射，而另一方会怎样？
这是我到目前为止得到的：
@Entity
@Table(name = "user")
data class User(
@Id
@GeneratedValue(generator = "my_user_sequence")
@SequenceGenerator(name = "my_user_sequence", sequenceName = "user_sequence", allocationSize = 1)
val id: Long = -1,
@JsonIgnore
@OneToOne(mappedBy = "user", cascade = [CascadeType.ALL], optional = false)
var preferences: Preferences? = null,
@OneToMany(cascade = [CascadeType.ALL])
var relationships: MutableSet<Relationship> = mutableSetOf(),
@Column(name = "facebook_id")
var fbId: String = "",
var email: String? = null,
var registrationToken: String = "",
var birthday: LocalDate? = null,
val created: LocalDateTime = LocalDateTime.now(Clock.systemUTC()),
@Column(name = "phone_number")
var phoneNumber: String = "",
var password: String? = null,
@Column(name = "first_name")
var firstName: String? = null,
@Column(name = "show_location")
var showLocation: Boolean = true,
@Column(name = "show_age")
var showAge: Boolean = true,
@Column(name = "picture_url")
var pictureUrl: String? = null,
@Column(name = "notify_message")
var notifyMessage: Boolean = true,
@Column(name = "notify_relationships")
var notifyRelationship: Boolean = true
)
这是关系类：
@Entity
@Table(name = "relationship")
data class Relationship(
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "joyship_relationship_sequence")
@SequenceGenerator(name = "joyship_relationship_sequence", sequenceName = "relationship_sequence", allocationSize = 1)
val id: Long = -1,
@ManyToOne(cascade = [])
@JoinTable(name = "first_party")
val firstParty: User,
@ManyToOne(cascade = [])
@JoinTable(name = "second_party")
val secondParty: User,
// Id of user is key for relationship_status of user with smaller number on id
@Enumerated(EnumType.STRING)
@Column(name = "first_status")
var firstStatus: RelationshipStatus = NOT_INTRODUCED,
// Id of user is key for relationship_status of user with bigger number on id
@Enumerated(EnumType.STRING)
@Column(name = "second_status")
var secondStatus: RelationshipStatus = NOT_INTRODUCED,
// Changes when relationship_status_1 or *_2 changes
// (Strongest of the statuses dictates common_relationship_status)
@Enumerated(EnumType.STRING)
@Column(name = "common_relationship_status")
var commonRelationshipStatus: RelationshipStatus = NOT_INTRODUCED,
@Column(name = "relative_distance")
var relativeDistance: Int = 160,
@Column
val established: LocalDateTime = LocalDateTime.now(Clock.systemUTC()),
@OneToOne(mappedBy = "relationship", cascade = [CascadeType.ALL], optional = false)
@JoinColumn(name = "last_interaction")
var lastInteraction: Interaction? = null,
@Column
var lastInteractionTime: LocalDateTime = LocalDateTime.now(Clock.systemUTC()))
当我尝试保持与用户的关系时，它始终为我提供这一点：
javax.persistence.PersistenceException: org.hibernate.PersistentObjectException: detached entity passed to persist: co.joyship.server.fraendurheim.models.Relationship
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:149)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:157)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:164)
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:814)
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:774)
at org.hibernate.jpa.event.internal.core.JpaPersistEventListener$1.cascade(JpaPersistEventListener.java:80)
at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:467)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:392)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:193)
at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:500)
at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:432)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:395)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:193)
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:126)
at org.hibernate.event.internal.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:445)
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:281)
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:182)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
at org.hibernate.jpa.event.internal.core.JpaPersistEventListener.saveWithGeneratedId(JpaPersistEventListener.java:67)
at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:189)
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:132)
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:58)
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:783)
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:768)
at org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager.persist(TestEntityManager.java:93)
at co.joyship.server.fraendurheim.RelationshipRepositoryTest.whenRequestingUserRelationshipFromDBReturnCorrectPagination(RelationshipRepositoryTest.kt:64)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:73)
at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:83)
at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: org.hibernate.PersistentObjectException: detached entity passed to persist: co.joyship.server.fraendurheim.models.Relationship
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:124)
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:807)
... 52 more
答案 0 :(得分：0)
如果有人发现自己的处境与我一样：不要尝试这种方法。据我的试验显示，不可能在一个实体中的两个 @ManyToOne和另一个实体中的 one @OneToMany之间建立双向关系。
到目前为止，针对我们的特定情况找到的两种解决方案是：
我使用this引用来正确设置@OneToMany关系