Need help in simplifying transaction based code

[Timothy Sam]

Hi guys! I'm really doubtful about this code here but it's the only thing that works for me as of now. I wanted this to be in a single transaction but I'm not sure how to do it.

  EntityManager em = getEntityManager();

      try 
      {
    em.getTransaction().begin();
          
    em.persist(fixedItem);
          
    em.getTransaction().commit();
          
          fixedItem = em.merge(fixedItem);
 
          /*Generate the control ID*/
          String controlId = null;
      
          /*Control ID format: <DATE><INVENTORY_TYPE><T><FIXED_INVENTORY_TYPE_ID><S><SUPPLIER_ID><F><INVENTORY_ID>*/
          /*INVENTORY_TYPE: F = fixed, C = Consumable,*/
          int itemTypeId = fixedItem.getFixedItemTypeId().getFixedItemTypeId();
          int supplierId = fixedItem.getSupplierId().getSupplierId();
          int fixedItemId = fixedItem.getFixedItemId();
          
          controlId = DateParser.getCurrentDate("yyyyMMdd") + "T" + itemTypeId + "S" + supplierId + "F" + fixedItemId;      
      
          fixedItem.setControlId(controlId);          
          
          //em.joinTransaction();
          em.getTransaction().begin();
          em.persist(fixedItem);
          
          em.getTransaction().commit();
 
          /*Create a log entry for item creation*/          
          InventoryTransactionType transactionType = new InventoryTransactionType();          
          
          transactionType.setTransactionTypeId(InventoryTransactionType.CREATE);
          
          InventoryTransaction inventoryLog = new InventoryTransaction();
          
          inventoryLog.setTransactionTypeId(transactionType);          
          inventoryLog.setUserId( fixedItem.getAssignedBy().getUserId() );
          //inventoryLog.setEmployeeId(null);
          inventoryLog.setControlId( fixedItem.getControlId() );
          inventoryLog.setDateCreated( new Date() );
 
          
          em.getTransaction().begin();
          em.persist(inventoryLog);
          em.getTransaction().commit();
 
          /*Also create a log for assignment*/
          inventoryLog = new InventoryTransaction();
          transactionType = new InventoryTransactionType();
          
          transactionType.setTransactionTypeId(InventoryTransactionType.ASSIGN);
          inventoryLog.setTransactionTypeId(transactionType);
          inventoryLog.setUserId( fixedItem.getAssignedBy().getUserId() ); 
                    
          Employee employee = new Employee();
          
          /*For some strange reason, employeeId is accessible from a null employee reference*/
          employee.setEmployeeId( fixedItem.getEmployeeId().getEmployeeId() );
          
          inventoryLog.setEmployeeId(employee);
          
          inventoryLog.setControlId( fixedItem.getControlId() );
          inventoryLog.setDateCreated( new Date() );
          
          
          em.getTransaction().begin();
          em.persist(inventoryLog);
          em.getTransaction().commit();
          
    addSuccessMessage("FixedItem was successfully created.");
  } 
      catch (Exception ex)
      {
    try 
          {
      addErrorMessage(ex.getLocalizedMessage());
      em.getTransaction().rollback();
    }
          catch (Exception e)
          {
      addErrorMessage(e.getLocalizedMessage());
    }
  } 
      finally
      {
    em.close();
  }

If you look at the code, you'll notice that I made an early commit, which I didn't want to do but I had no choice because I wanted to get the generated ID to be able to produce a controlId String.


You'll also notice that I made many commit statements which makes the rollback in the try-catch block useless because changes are already reflected to the database when an exception is thrown. I really want to avoid this so I want to put them all in a single transaction and rollback everything if an exception occurs. Many thanks!

[Mike Keith]

Hi Timothy,

The problem of obtaining a generated id before commit can be solved by issuing a flush call, so I would normally recommend that you do that, however, looking at your code I have to say (and no offence intended) that you might really want to so some more reading on JPA before going any further. I think you would find that a small investment of a day or two would really pay dividends. Pick up any book on JPA (I can recommend one ;-) that takes your fancy and learn when and how to use which EntityManager operations, etc.

[Timothy Sam]

Thanks! It worked! I adjust my code like the following:

  EntityManager em = getEntityManager();

      try 
      {
    em.getTransaction().begin();
          
    em.persist(fixedItem);
 
          em.flush();
          
          fixedItem = em.merge(fixedItem);
 
          /*Generate the control ID*/
          String controlId = null;
      
          /*Control ID format: <DATE><INVENTORY_TYPE><T><FIXED_INVENTORY_TYPE_ID><S><SUPPLIER_ID><F><INVENTORY_ID>*/
          /*INVENTORY_TYPE: F = fixed, C = Consumable,*/
          int itemTypeId = fixedItem.getFixedItemTypeId().getFixedItemTypeId();
          int supplierId = fixedItem.getSupplierId().getSupplierId();
          int fixedItemId = fixedItem.getFixedItemId();
          
          controlId = DateParser.getCurrentDate("yyyyMMdd") + "T" + itemTypeId + "S" + supplierId + "F" + fixedItemId;      
      
          fixedItem.setControlId(controlId);          
 
          em.persist(fixedItem);
 
          /*Create a log entry for item creation*/          
          InventoryTransactionType transactionType = new InventoryTransactionType();          
          
          transactionType.setTransactionTypeId(InventoryTransactionType.CREATE);
          
          InventoryTransaction inventoryLog = new InventoryTransaction();
          
          inventoryLog.setTransactionTypeId(transactionType);          
          inventoryLog.setUserId( fixedItem.getAssignedBy().getUserId() );
          inventoryLog.setControlId( fixedItem.getControlId() );
          inventoryLog.setDateCreated( new Date() );
 

          em.persist(inventoryLog);
 

          /*Also create a log for assignment*/
          inventoryLog = new InventoryTransaction();
          transactionType = new InventoryTransactionType();
          
          transactionType.setTransactionTypeId(InventoryTransactionType.ASSIGN);
          inventoryLog.setTransactionTypeId(transactionType);
          inventoryLog.setUserId( fixedItem.getAssignedBy().getUserId() ); 
                    
          Employee employee = new Employee();
          
          /*For some strange reason, employeeId is accessible from a null employee reference*/
          employee.setEmployeeId( fixedItem.getEmployeeId().getEmployeeId() );
          
          inventoryLog.setEmployeeId(employee);
          
          inventoryLog.setControlId( fixedItem.getControlId() );
          inventoryLog.setDateCreated( new Date() );
          
          em.persist(inventoryLog);
          em.getTransaction().commit();
          
    addSuccessMessage("FixedItem was successfully created.");
  } 
      catch (Exception ex)
      {
    try 
          {
      addErrorMessage(ex.getLocalizedMessage());
      em.getTransaction().rollback();
    }
          catch (Exception e)
          {
      addErrorMessage(e.getLocalizedMessage());
    }
  } 
      finally
      {
    em.close();
  }

I can see that you have written a book? My friend whom I ask to order for me isn't with me anymore so I won't be able to get stuff on the internet anytime soon. Thanks a lot for the help BTW!