fetch lazy collection without initialize

[nimo frey]

I have a collection with lazy fetch and want to fetch the collection within a session:

So I tried this, but that does not hit the database to fetch the collection:

User u = em.find...

// 1. way: fetch lazy collection so that this collection is fetch into the session
u.getHobbies();

// 2. way: however when using this, the collection is fetched into the session
System.out.println(u.getHobbies());

// 3. way: when using this, the collection is also fetched into the session
Hibernate.initialize(u.getHobbies());

Why does 1.way not work?

How would I do the "Hibernate.initialize" normally in JPA 2-standard?

[Paul Sturrock]

My guess is you have a collection of proxies until you call a method on those proxies (I'm assuming the implicit call to toString() is the method). Can't say for sue without reading the Hibernate source. Just out of curiosity, why would you ever need to do 1? Do you have occasions where you want to return data from the database and do nothing with it?

How would I do the "Hibernate.initialize" normally in JPA 2-standard?

You can't, but again I can't think of a case where you might need to. Am I missing something?

[nimo frey]

I want to fetch my collections via a condition, so annotating my collection with FetchType.EAGER is not usefull in this case.

I only want to touch the collection so it is fetched - the collection is not used within the same transaction so it automatically gets unmanaged - which is what I want!
(I also cannot use a separate query with "left join fetch" as there are more than one collections..)

// this does work but I do not need to log the collections
if(fetchCollections){

System.out.println(u.getHobbies()); 

}

so I use this, which works fine in my case:

if(fetchCollections){

Hibernate.initialize(u.getHobbies());

}

However, Hibernate.initialize is not JPA-Standard-conform.

However, it works;) thanks.

[Paul Sturrock]

I want to fetch my collections via a condition, so annotating my collection with FetchType.EAGER is not usefull in this case.

Any reason you don't just eagerly fetch your query based on the same condition?

[nimo frey]

Any reason you don't just eagerly fetch your query based on the same condition?

I cannot use a separate query with "left join fetch" as there are more than one collections which I want to fetch:

select .. from x left join fetch x.coll1 left join fetch x.coll2 left join fetch x.coll2 left join fetch x.coll4 where ...

It is far faster to initialize the collections via

Hibernate.initialize(x.getColl1()); 
Hibernate.initialize(x.getColl2());  
..

instead of using the above query.