EntityExistsException when reset a ArrayList and refill before merge

Hibernate ORM
2

There are two ways to fix it:

  1. The fastest way but not the most efficient is to just flush after resetting the collection:

    pedido.setItens(new ArrayList<>());

entityManager.flush();

nfeFiltro.getProdutos().stream()
		.forEach(nfeProduto -> {
			PedidoItem pedidoItem = new PedidoItem();
			pedidoItem.setPedido(pedido);

			PedidoItemId pedidoItemId = new PedidoItemId();
			pedidoItemId.setPedidoLinha(nfeProduto.getId().getNfeNumeroDoItem());
			pedidoItem.setId(pedidoItemId);

// fill the pedidoItem

  2. The more efficient and the proper way to do it is to merge the old and the new collection so that:

    • items that are both in the old and the new collection should not be removed
    • new items are added from the incoming collection to the managed one
    • old entries that are no longer found in the incoming collection should be removed

For more details, check out this article.