[jboss-user] [JBoss Seam] - Batch removing, conversations and transactions managment

[v.masterov@gmail.com]

I have a question concerning batch entity deletion. I need to delete multiple entities at once, while some of them have references to other entities. When I try to delete a group of entities without any references, the operation is successful. But if at least one of the entities in the batch has references, the transaction is rolled back entirely. What I am trying to do is to delete all the entities without references, while the others (entites in the batch with references) can be left unchanged. I am trying to delete entities using separate transactions for each entity, but still fail. JBoss Seam tutorial mentions manual transaction management through conversation management (using the annotations @Begin(flushMode = FlushModeType.MANUAL) and @End).
I am trying to perform deletion using the two beans. The first bean implies cycle iteration with all ids and EntityManager is not injected into this bean. A separate deletion is performed within the second bean, this one injects EntityManager. It is not clear how to manage conversations. Both beans are conversation beans. After the first iteration the first bean is performed in the conversation context declared in the second bean, i.e. "join = true". If I declare "join = false" the first iteration returns exception:"java.lang.IllegalStateException: begin method invoked from a long running conversation, try using @Begin(join=true) on method: remove". With "join = true" each next iteration is performed within the same conversation, and as far as I understand in the same transaction. This results in entire rollback of all deletion operations.  Please, help me !!! What is the right way to do this ?


  | import java.util.*;
  | import org.jboss.seam.Component;
  | import org.jboss.seam.ScopeType;
  | import org.jboss.seam.annotations.*;
  | import org.jboss.seam.contexts.Contexts;
  | import org.jboss.seam.core.Conversation;
  | import org.jboss.seam.log.Log;
  | 
  | @Name("entityGroupRemover")
  | @Scope(ScopeType.CONVERSATION)
  | public class EntityGroupRemover {
  | 	
  | 		
  | 	@Create
  | 	@Begin(id = "groupRemoverConversation", join = true)
  | 	public void remove(Long[] ids, Class entityClass) {
  | 		for (int i = 0; i < ids.length; i++) {						
  | 			try {
  | 				log.info("conversationId = " + Conversation.instance().getId());
  | 				SingleEntityRemover remover = (SingleEntityRemover)Component.getInstance("singleEntityRemover",
  |  ScopeType.CONVERSATION, true);
  | 				remover.removeSingleEntity(ids, entityClass);
  | 				remover.commit();
  | 			} catch(Exception e) {
  | 				e.printStackTrace();
  | 			}
  | 		}
  | 		Conversation.instance().end(true);		
  | 	}
  | 			
  | 	
  | }
  | 


  | import javax.persistence.EntityManager;
  | import org.jboss.seam.ScopeType;
  | import org.jboss.seam.annotations.*;
  | import org.jboss.seam.contexts.Contexts;
  | import org.jboss.seam.core.Conversation;
  | import org.jboss.seam.core.Messages;
  | import org.jboss.seam.log.Log;
  | 
  | @Name("singleEntityRemover")
  | @Scope(ScopeType.CONVERSATION)
  | public class SingleEntityRemover {
  | 	
  | 	@Logger
  | 	Log log;
  | 		
  | 	@In(value = "entityManager")
  | 	EntityManager em;
  | 	
  | 	@Begin(id = "singleRemoverConversation", flushMode = FlushModeType.MANUAL, join = false, nested = true)
  | 	public void removeSingleEntity(Long id, Class entityClass) {
  | 		log.info("conversationId = " + Conversation.instance().getId());
  | 		Object entity = em.find(entityClass, id);
  | 		em.remove(entity);
  | 	}
  | 	
  | 	@End
  | 	public void commit() throws Exception {
  | 		try {		
  | 			em.flush();	
  | 			log.info("transaction successed !!!");
  | 		} catch(Exception e) {
  | 			log.info("transaction failed !!!");
  | 			throw  e;
  | 		}		
  | 	}
  | 	
  | }
  | 

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