Design question:why a component can't be lazily initialized?

replix · **Joined:** Mon Jul 26, 2004 4:55 am **Posts:** 4

Hi all,

Example of use :

I want to store files in the database. For performance reasons, I want to be able to retrieve the name of the file without loadind its data.

The solution would be to :
* have a File class with its properties (name, type, ...) and a FileData class with the bytes. There is a one to one relation beetween the 2 classes.
* map the 2 classes on the same table, FileData being a lazy loaded component of File.

Does it makes sense? Someone with a better idea for this mapping?

Thanks,
Gaetan

emmanuel · **Posted:** Tue Oct 19, 2004 5:36 am

check the lightweight pattern in the wiki area

replix · **Joined:** Mon Jul 26, 2004 4:55 am **Posts:** 4

Thanks a lot. It is exactly what I want to do.

replix · **Joined:** Mon Jul 26, 2004 4:55 am **Posts:** 4

However, the LightWeigh pattern is a way of resolving the problem. But sometimes delegation is a best pattern and allowing lazy init on component would be great.

emmanuel · **Posted:** Sat Nov 06, 2004 6:29 am

You can do that on H3
From the roadmap

Quote:

Column-level lazy fetching (done)

This is a checkbox feature that Hibernate needs for marketing purposes. Any property may be marked lazy="true", and will be fetched from the database when the field is first accessed. This feature requires build-time bytecode instrumentation using an Ant task. If Hibernate encounters uninstrumented classes at runtime, the feature will be transparently disabled.