JPA：deleteAll條目，然後在一個事務中重新創建單個條目

Question

我遇到了問題，我想從一個表中刪除所有條目，然後重新創建與從頭刪除的ID相同的單個項目。這應該在一個事務中，以便該表永遠不會爲空。

提示：我使用Spring Batch並通過chunk listener在beforeChunk之前（它在事務內部）刪除talbe，讀寫器隨後運行以保留新版本的數據。

Currentely，如果我這樣做，我收到此錯誤：

Encountered an error executing step importXXXXX in job jobXXXX java.lang.IllegalArgumentException: Cannot merge an Entity that has been removed

堆棧跟蹤：

at org.eclipse.persistence.internal.sessions.MergeManager.registerObjectForMergeCloneIntoWorkingCopy(MergeManager.java:1070) ~[eclipselink-2.6.4.jar:2.6.4.v20160829-44060b6] 
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChangesOfCloneIntoWorkingCopy(MergeManager.java:564) ~[eclipselink-2.6.4.jar:2.6.4.v20160829-44060b6] 
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChanges(MergeManager.java:313) ~[eclipselink-2.6.4.jar:2.6.4.v20160829-44060b6] 
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.mergeCloneWithReferences(UnitOfWorkImpl.java:3521) ~[eclipselink-2.6.4.jar:2.6.4.v20160829-44060b6] 
at org.eclipse.persistence.internal.sessions.RepeatableWriteUnitOfWork.mergeCloneWithReferences(RepeatableWriteUnitOfWork.java:387) ~[eclipselink-2.6.4.jar:2.6.4.v20160829-44060b6] 
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.mergeCloneWithReferences(UnitOfWorkImpl.java:3481) ~[eclipselink-2.6.4.jar:2.6.4.v20160829-44060b6] 
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.mergeInternal(EntityManagerImpl.java:553) ~[eclipselink-2.6.4.jar:2.6.4.v20160829-44060b6] 
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.merge(EntityManagerImpl.java:530) ~[eclipselink-2.6.4.jar:2.6.4.v20160829-44060b6] 
at org.springframework.batch.item.database.JpaItemWriter.doWrite(JpaItemWriter.java:104) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.item.database.JpaItemWriter.write(JpaItemWriter.java:83) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.step.item.SimpleChunkProcessor.writeItems(SimpleChunkProcessor.java:175) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.step.item.SimpleChunkProcessor.doWrite(SimpleChunkProcessor.java:151) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.step.item.SimpleChunkProcessor.write(SimpleChunkProcessor.java:274) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.step.item.SimpleChunkProcessor.process(SimpleChunkProcessor.java:199) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.step.item.ChunkOrientedTasklet.execute(ChunkOrientedTasklet.java:75) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:406) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:330) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:133) ~[spring-tx-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
at org.springframework.batch.core.step.tasklet.TaskletStep$2.doInChunkContext(TaskletStep.java:271) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.scope.context.StepContextRepeatCallback.doInIteration(StepContextRepeatCallback.java:81) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.repeat.support.RepeatTemplate.getNextResult(RepeatTemplate.java:374) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.repeat.support.RepeatTemplate.executeInternal(RepeatTemplate.java:215) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.repeat.support.RepeatTemplate.iterate(RepeatTemplate.java:144) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.step.tasklet.TaskletStep.doExecute(TaskletStep.java:257) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:200) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.job.SimpleStepHandler.handleStep(SimpleStepHandler.java:148) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.job.flow.JobFlowExecutor.executeStep(JobFlowExecutor.java:64) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.job.flow.support.state.StepState.handle(StepState.java:67) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.job.flow.support.SimpleFlow.resume(SimpleFlow.java:169) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.job.flow.support.SimpleFlow.start(SimpleFlow.java:144) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.job.flow.FlowJob.doExecute(FlowJob.java:134) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:306) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.batch.core.launch.support.SimpleJobLauncher$1.run(SimpleJobLauncher.java:135) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 
at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50) [spring-core-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:128) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE] 

你有一個想法，persit入口雖然在已經被刪除這個交易。

謝謝！

Answer 1

的specification具有以下部分中說3.2.4.1合併獨立屋實體狀態：

If X is a removed entity instance, an IllegalArgumentException will be thrown by the merge operation (or the transaction commit will fail).

它還說，在部分3.2.1堅持實體實例：

If X is a removed entity, it becomes managed.

並進一步在之下3.2.3同步到數據庫：

If X is a managed entity, it is synchronized to the database.

[...]

• If X is a removed entity, it is removed from the database. No cascade options are relevant.

因此，您嘗試使用JPA似乎不太可能。一個解決辦法可能是我的評論中建議的實體重用。