Is there an easier way to load graphs than my example?

egervari · **Joined:** Sun Oct 26, 2003 5:05 am **Posts:** 139

Hi guys,

I'm wondering if there is a cleaner way to initialize object graphs. This is what I'm doing now:

Code:

            UserRole userRole = (UserRole) reflectable;

            if( loadPrivileges ) {
               Hibernate.initialize( userRole.getPrivileges() );

               if( loadPages ) {
                  Iterator i = userRole.getPrivileges().iterator();
                  while( i.hasNext() ) {
                     UserPrivilege privilege = (UserPrivilege) i.next();
                     Hibernate.initialize( privilege.getPages() );
                  }
               }
            }

This is kind of verbose for something sort of simple, so I take it I'm doing something wrong (like I don't know about a feature, etc.). I'd appreciate it if you could give me some tips. Thanks so much.

dplass · **Posted:** Tue Aug 17, 2004 11:11 pm

First off, can you post your mapping and java code?

Secondly, it seems that (as an example from your examples), getPrivileges returns a Collection. Lets say for the sake of argument, it's a List. Then why not map it as a List?

Then you could just say

Code:

session.doLoad(user, id);

Or somesuch equivalent in your (static) Hibernate class.

egervari · **Joined:** Sun Oct 26, 2003 5:05 am **Posts:** 139

dplass wrote:

First off, can you post your mapping and java code?

Secondly, it seems that (as an example from your examples), getPrivileges returns a Collection. Lets say for the sake of argument, it's a List. Then why not map it as a List?

Then you could just say

Code:

session.doLoad(user, id);

Or somesuch equivalent in your (static) Hibernate class.

Well, I figure the structure of the objects is pretty self explanatory. I use lazy-load for all many-to-many relationships. Here, a role contains privileges and a privilege contains pages.

Secondly, that is Hibernate's static class, not mine. It's a method that is meant to eagerly fetch collections marked as lazy in the xml mapping files.

Also, there is nothing here that says it's a list. In fact, it makes sense that privileges would be modeled as a set since privileges usually don't apply in any order (or at least in my application anyway). Besides, loading strategies are pretty independant of all of these details anyway - a collection is a collection.

Of well, I guess I'll keep doing it this way unless I find a better way.

anthony · **Posted:** Wed Aug 18, 2004 7:39 am

show mapping file

christian · **Posted:** Wed Aug 18, 2004 7:43 am

Guys, don't make it complex: He has a collection of entities and each entity again has a collection. He likes to fetch it all. This will be 1 outer-join select for the root entity and the first collection, and N selects for each secondary collection:

First:
"from Role r left join fetch r.privileges" (or use Criteria FetchMode)

Second:
iterate collection r.privileges: Hibernate.initialize(privilege.getPages());
OR
just let Hibernate load it once it is first accessed

You may use a batch-size on the privilege mapping to optimize the lazy loading.

Thats it, it doesn't get better than this.

christian · **Posted:** Wed Aug 18, 2004 7:45 am

Ups, wrong: batch size on the _pages_ collection mapping...

dplass · **Posted:** Wed Aug 18, 2004 8:51 am

christian wrote:

just let Hibernate load it once it is first accessed

Is what I was going for. That's how I plan on doing it in my forthcoming rollout of Hibernate. Why make things hard? You guys did all the hard word (thanks, BTW) for us!

dplass · **Posted:** Wed Aug 18, 2004 8:52 am

Oops, I meant

s/word/work/

egervari · **Joined:** Sun Oct 26, 2003 5:05 am **Posts:** 139

Thanks Christian. That's exactly what I wanted to know.