Running through entities relation tree instead of sending specific DAO queries

as you know, in Seam there are no problems with LazyInitializationException when reading entities's references to subobjects. So is there any problem if I favor running through the tree of relations in order to read the data that I need, instead of sending specific queries to releveant entities' DAOs? Do I break som开发者_StackOverflow中文版e important guidelinies/priciples?

Consider that the phrase:

"in Seam there are no problems with LazyInitializationException"

It's not true.

In seam there are no problems with LazyInitializationException if you use a pattern where your session is being persisted in the boundary of a long-running conversation.

This means using a Seam injected persistence context like:

@In
private EntityManager entityManager;

Or, if you are using stateful EJBs (bound to conversation scope too):

@PersistenceContext(type = PersistenceContextType.EXTENDED) EntityManager em;

BTW, once you have understand that, there is no problem navigating the relation tree. You should really do it, if you want to bind it to the interface using JSF.

Consider that you may incur in some speed problem if you access to ManyToOne or OneToMany relations in queries that returns more than one result. This is known as n+1 problem, when you basically runs one more roundtrip to the database for each record returned.

Let's summarize:

• single detail object -> navigate relation tree
• List of other object -> make a single query to the DAO using left join fetch.