我正在基于 JavaEE + JPA 的 JBoss 服务器上构建 Rest-API。
我有两个名为“Mitglied”和“Einsatz”的实体:
@Entity
@Table(name="MITGLIEDER")
public class Mitglied implements Serializable{
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
// bunch of more attributes
@ManyToMany(mappedBy="teilnehmendeMitglieder")
private Set<Einsatz> einsaetze;
public Set<Einsatz> getEinsaetze() {
return einsaetze;
}
public void setEinsaetze(Set<Einsatz> einsaetze) {
this.einsaetze = einsaetze;
}
public void addEinsatz(Einsatz e) {
addEinsatz(e, true);
}
public void addEinsatz(Einsatz b, boolean set) {
if (einsaetze == null) {
einsaetze = new HashSet<Einsatz>();
}
if (b != null) {
getEinsaetze().add(b);
if (set) {
b.addMitglied(this, false);
}
}
}
public void removeEinsatz(Einsatz e) {
removeEinsatz(e, true);
}
public void removeEinsatz(Einsatz e, boolean cascade) {
getErworbeneDienstgrade().remove(e);
if (cascade) {
e.removeMitglied(this, false);
}
}
// more getters and setters
}
这里是“Einsatz”:
@Entity
@Table(name="EINSAETZE")
public class Einsatz implements Serializable {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
// some more attributes
@ManyToMany
@JoinTable(name = "MITGLIED_HAT_AN_EINSATZ_TEILGENOMMEN",
joinColumns = {@JoinColumn( name = "EINSATZ_ID", referencedColumnName = "ID" )}, // ID ist die Id von Einsatz
inverseJoinColumns = {@JoinColumn( name = "MITGLIED_ID", referencedColumnName = "ID" )} // ID ist die Id von Mitglied
)
private Set<Mitglied> teilnehmendeMitglieder;
private static final long serialVersionUID = 1L;
public Einsatz() {
super();
}
public int getId() {
return this.id;
}
public void setId(int id) {
this.id = id;
}
public void removeMitglied(Mitglied m) {
removeMitglied(m, true);
}
public void removeMitglied(Mitglied m, boolean cascade) {
if (teilnehmendeMitglieder!= null && teilnehmendeMitglieder.contains(m)) {
teilnehmendeMitglieder.remove(m);
}
if (cascade) {
m.removeEinsatz(this, false);
}
}
public void addMitglied(Mitglied m) {
addMitglied(m, true);
}
public void addMitglied(Mitglied b, boolean set) {
if (teilnehmendeMitglieder == null) {
teilnehmendeMitglieder = new HashSet<Mitglied>();
}
if (b != null) {
getTeilnehmendeMitglieder().add(b);
if (set) {
b.addEinsatz(this, false);
}
}
}
// more getters and setters
}
这是我的问题:
在尝试将 Mitglied 分配给 Einsatz 时，Hibernate 会尝试将关系两次插入连接表(“MITGLIED_HAT_AN_EINSATZ_TEILGENOMMEN”)，这会导致约束违规。
我尝试了各种级联类型和星座，例如米特利作为关系所有者，对我来说没有任何作用。搜索SO给了我一些提示，即使如此也没有解决问题。我到目前为止，至少第一条记录被写入 MySQL-DB，尽管我不断收到 ConstraintViolationException...
我敢肯定，这是非常愚蠢的事情，但我又看不出这一点。我究竟做错了什么？我得到的只是:
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '39-1' for key 'PRIMARY'
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) [rt.jar:1.7.0_21]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) [rt.jar:1.7.0_21]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) [rt.jar:1.7.0_21]
at java.lang.reflect.Constructor.newInstance(Constructor.java:525) [rt.jar:1.7.0_21]
at [... and so on ...]
这是导致此错误的业务逻辑:
public void assignMitgliedToEinsatz(int mitgliedId, int einsatzId){
Mitglied m = mitgliederDao.getMitglied(mitgliedId);
Einsatz e = dao.readIt(einsatzId, Einsatz.class);
e.addMitglied(m);
dao.updateIt(e); // calls JPAs merge() method
}
编辑:
我尝试了 Kikin-Sama 的将字段设置为 transient 的建议，但错误仍然存在。这里有一些关于 hibernate-logs 的详细错误:
21:07:19,544 INFO [stdout] (default task-8) Hibernate:
21:07:19,545 INFO [stdout] (default task-8) insert
21:07:19,545 INFO [stdout] (default task-8) into
21:07:19,545 INFO [stdout] (default task-8) MITGLIED_HAT_AN_EINSATZ_TEILGENOMMEN
21:07:19,545 INFO [stdout] (default task-8) (EINSATZ_ID, MITGLIED_ID)
21:07:19,545 INFO [stdout] (default task-8) values
21:07:19,545 INFO [stdout] (default task-8) (?, ?)
21:07:19,545 INFO [stdout] (default task-9) Hibernate:
21:07:19,545 INFO [stdout] (default task-9) insert
21:07:19,545 INFO [stdout] (default task-9) into
21:07:19,545 INFO [stdout] (default task-9) MITGLIED_HAT_AN_EINSATZ_TEILGENOMMEN
21:07:19,545 INFO [stdout] (default task-9) (EINSATZ_ID, MITGLIED_ID)
21:07:19,545 INFO [stdout] (default task-9) values
21:07:19,545 INFO [stdout] (default task-9) (?, ?)
21:07:19,547 WARN [org.hibernate.engine.jdbc.spi.SqlExceptionHelper] (default task-9) SQL Error: 1062, SQLState: 23000
21:07:19,548 ERROR [org.hibernate.engine.jdbc.spi.SqlExceptionHelper] (default task-9) Duplicate entry '99-1' for key 'PRIMARY'
21:07:19,549 INFO [org.hibernate.engine.jdbc.batch.internal.AbstractBatchImpl] (default task-9) HHH000010: On release of batch it still contained JDBC statements
21:07:19,550 WARN [com.arjuna.ats.arjuna] (default task-9) ARJUNA012125: TwoPhaseCoordinator.beforeCompletion - failed for SynchronizationImple< 0:ffff7f000101:497b6818:54c7efdd:bf, org.hibernate.engine.transaction.synchronization.internal.RegisteredSynchronization@d5d8750 >: javax.persistence.PersistenceException: org.hibernate.exception.ConstraintViolationException: could not execute statement
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1763) [hibernate-entitymanager-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1677) [hibernate-entitymanager-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1683) [hibernate-entitymanager-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.jpa.spi.AbstractEntityManagerImpl$CallbackExceptionMapperImpl.mapManagedFlushFailure(AbstractEntityManagerImpl.java:1882) [hibernate-entitymanager-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.engine.transaction.synchronization.internal.SynchronizationCallbackCoordinatorNonTrackingImpl.beforeCompletion(SynchronizationCallbackCoordinatorNonTrackingImpl.java:115) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.engine.transaction.synchronization.internal.RegisteredSynchronization.beforeCompletion(RegisteredSynchronization.java:50) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at com.arjuna.ats.internal.jta.resources.arjunacore.SynchronizationImple.beforeCompletion(SynchronizationImple.java:76) [narayana-jts-jacorb-5.0.0.Final.jar:5.0.0.Final (revision: 9aa71)]
at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.beforeCompletion(TwoPhaseCoordinator.java:358) [narayana-jts-jacorb-5.0.0.Final.jar:5.0.0.Final (revision: 9aa71)]
at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.end(TwoPhaseCoordinator.java:91) [narayana-jts-jacorb-5.0.0.Final.jar:5.0.0.Final (revision: 9aa71)]
at com.arjuna.ats.arjuna.AtomicAction.commit(AtomicAction.java:162) [narayana-jts-jacorb-5.0.0.Final.jar:5.0.0.Final (revision: 9aa71)]
at com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1166) [narayana-jts-jacorb-5.0.0.Final.jar:5.0.0.Final (revision: 9aa71)]
at com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.commit(BaseTransaction.java:126) [narayana-jts-jacorb-5.0.0.Final.jar:5.0.0.Final (revision: 9aa71)]
at com.arjuna.ats.jbossatx.BaseTransactionManagerDelegate.commit(BaseTransactionManagerDelegate.java:75)
at com.arjuna.ats.jta.cdi.transactional.TransactionalInterceptorBase.endTransaction(TransactionalInterceptorBase.java:147) [narayana-jts-jacorb-5.0.0.Final.jar:5.0.0.Final (revision: 9aa71)]
at com.arjuna.ats.jta.cdi.transactional.TransactionalInterceptorBase.invokeInOurTx(TransactionalInterceptorBase.java:93) [narayana-jts-jacorb-5.0.0.Final.jar:5.0.0.Final (revision: 9aa71)]
at com.arjuna.ats.jta.cdi.transactional.TransactionalInterceptorRequired.intercept(TransactionalInterceptorRequired.java:52) [narayana-jts-jacorb-5.0.0.Final.jar:5.0.0.Final (revision: 9aa71)]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_21]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) [rt.jar:1.7.0_21]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_21]
at java.lang.reflect.Method.invoke(Method.java:601) [rt.jar:1.7.0_21]
at org.jboss.weld.interceptor.proxy.SimpleMethodInvocation.invoke(SimpleMethodInvocation.java:30) [weld-core-impl-2.1.2.Final.jar:2014-01-09 09:23]
at org.jboss.weld.interceptor.chain.AbstractInterceptionChain.invokeNext(AbstractInterceptionChain.java:103) [weld-core-impl-2.1.2.Final.jar:2014-01-09 09:23]
at org.jboss.weld.interceptor.chain.AbstractInterceptionChain.invokeNextInterceptor(AbstractInterceptionChain.java:81) [weld-core-impl-2.1.2.Final.jar:2014-01-09 09:23]
at org.jboss.weld.interceptor.proxy.InterceptorMethodHandler.executeInterception(InterceptorMethodHandler.java:48) [weld-core-impl-2.1.2.Final.jar:2014-01-09 09:23]
at org.jboss.weld.interceptor.proxy.InterceptorMethodHandler.invoke(InterceptorMethodHandler.java:41) [weld-core-impl-2.1.2.Final.jar:2014-01-09 09:23]
at org.jboss.weld.bean.proxy.CombinedInterceptorAndDecoratorStackMethodHandler.invoke(CombinedInterceptorAndDecoratorStackMethodHandler.java:53) [weld-core-impl-2.1.2.Final.jar:2014-01-09 09:23]
at de.florian.remote.mitglieder.EinsaetzeRemote$Proxy$_$$_WeldSubclass.assignEinsatzToMitglied(Unknown Source) [classes:]
at de.florian.remote.mitglieder.EinsaetzeRemote$Proxy$_$$_WeldClientProxy.assignEinsatzToMitglied(Unknown Source) [classes:]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_21]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) [rt.jar:1.7.0_21]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_21]
at java.lang.reflect.Method.invoke(Method.java:601) [rt.jar:1.7.0_21]
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81) [jersey-server-2.13.jar:]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:151) [jersey-server-2.13.jar:]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:171) [jersey-server-2.13.jar:]
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$TypeOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:195) [jersey-server-2.13.jar:]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:104) [jersey-server-2.13.jar:]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:384) [jersey-server-2.13.jar:]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:342) [jersey-server-2.13.jar:]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:101) [jersey-server-2.13.jar:]
at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:271) [jersey-server-2.13.jar:]
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271) [jersey-common-2.13.jar:]
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267) [jersey-common-2.13.jar:]
at org.glassfish.jersey.internal.Errors.process(Errors.java:315) [jersey-common-2.13.jar:]
at org.glassfish.jersey.internal.Errors.process(Errors.java:297) [jersey-common-2.13.jar:]
at org.glassfish.jersey.internal.Errors.process(Errors.java:267) [jersey-common-2.13.jar:]
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:297) [jersey-common-2.13.jar:]
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:254) [jersey-server-2.13.jar:]
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1030) [jersey-server-2.13.jar:]
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:373) [jersey-container-servlet-core-2.13.jar:]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:381) [jersey-container-servlet-core-2.13.jar:]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:344) [jersey-container-servlet-core-2.13.jar:]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:221) [jersey-container-servlet-core-2.13.jar:]
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:61) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:113) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:56) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:61) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:58) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:70) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:240) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:227) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:73) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:146) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:177) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:727) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_21]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_21]
at java.lang.Thread.run(Thread.java:722) [rt.jar:1.7.0_21]
Caused by: org.hibernate.exception.ConstraintViolationException: could not execute statement
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:72) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:190) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:62) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.persister.collection.AbstractCollectionPersister.insertRows(AbstractCollectionPersister.java:1531) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.action.internal.CollectionUpdateAction.execute(CollectionUpdateAction.java:102) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:463) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:349) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:350) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:56) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1222) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:425) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
at org.hibernate.engine.transaction.synchronization.internal.SynchronizationCallbackCoordinatorNonTrackingImpl.beforeCompletion(SynchronizationCallbackCoordinatorNonTrackingImpl.java:110) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
... 74 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '99-1' for key 'PRIMARY'
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) [rt.jar:1.7.0_21]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) [rt.jar:1.7.0_21]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) [rt.jar:1.7.0_21]
at java.lang.reflect.Constructor.newInstance(Constructor.java:525) [rt.jar:1.7.0_21]
at com.mysql.jdbc.Util.handleNewInstance(Util.java:408)
at com.mysql.jdbc.Util.getInstance(Util.java:383)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1049)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4208)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4140)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2597)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2758)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2826)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2082)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2334)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2262)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2246)
at org.jboss.jca.adapters.jdbc.CachedPreparedStatement.executeUpdate(CachedPreparedStatement.java:119)
at org.jboss.jca.adapters.jdbc.WrappedPreparedStatement.executeUpdate(WrappedPreparedStatement.java:493)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:187) [hibernate-core-4.3.5.Final.jar:4.3.5.Final]
... 84 more
最佳答案
好的，明白了! 对 SO 的一些拼命研究让我想到了这个问题:
JPA many-to-many persist to join table (参见 Ravi Thapliyal 的回答)
简而言之，我必须将 cascade = CascadeType.PERSIST 添加到关系的 Mitglied 一侧，所以这就是我的情况:
// Code from class "Mitglied" and "Einsatz"same as in Question,
// but this annotation in Mitglied:
@ManyToMany(mappedBy="teilnehmendeMitglieder", cascade=CascadeType.PERSIST)
private Set<Einsatz> einsaetze;
关于java - JPA双向@ManyToMany关系: Assignment causes two inserts，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/28177911/