将持久化实体保留在事务之外

Question

I have a scenario where I am trying to import complex data to my database (objects with child objects and list objects, some for updates while others for new inserts). Right now, the general process I'm working with is the following:

void importData(List dataToImport){
     Object persistedObject1 = getObjectFromDB(); // data that will be attached to various objects in my import
     HashMap map1 = preFillMap1();  // Fills a map with persisted objects from database to be attached to data
     HashMap map2 = emptyMap(); // start with an empty map here
     try{
         for(Object data : dataToImport){
                Object dbSavedData = importDataImpl(persistedObject1, map2, map3, data)
                map2.put(dbSavedData.getChild().getRecordID(), dbSavedData.getChild())
         }
     }catch(Exception e){
           logger.error("Error in transaction", e);
     }
}

@org.springframework.transaction.annotation.Transactional
void importDataImpl(Object persistedObj, HashMap map1, HashMap map2, Object dataToImport){
      // simplified import process
      dataToImport.setForeignKeyObject1(persistedObj);
      dataToImport.setForeignKeyObject2(map1.get(dataToImport.obj2ID));
      if(map2.contains(dataToImport.getChild().getRecordID()){
            dataToImport.setForeignKeyObject3(map2.get(dataToImport.obj3ID));
      }else{
            dataToImport.setForeignKeyObject3(repo.findByID(dataToImport.getChild().getRecordID());
      }
      jpaRepo.save(dataToImport);           
}

The problem I'm running into in the above is that once I hit an error in importDataImpl, I run into an error for future calls with the following:

detached entity passed to persist: com.project.ChildObject; nested exception is org.hibernate.PersistentObjectException: 
detached entity passed to persist: com.project.ChildObject org.springframework.dao.InvalidDataAccessApiUsageException: detached entity passed to persist:com.project.ChildObject

The only way so far I've been able to work around it is to reset the maps on error and retry the importDataImpl call. It works the second time around without an issue, but the goal of keeping the maps is to reduce the number of DB calls needed. I've seen some recommendations on doing an entityManager.contains(obj) check, but this isn't reliable from what I can tell nor is it the most elegant solution either as I would still have to reset the maps. At that point, catching the error and handling it there seems more cleaner.

Answer 1

Perhaps you could try entity.merge().

merge() will push the stale state to the DB, and overwrite any intervening updates