im confused, in the docs it says that this is a proxy:

proxy (optional): Specifies an interface to use for lazy initializing proxies. You may specify the name of the class itself.

how and when should I use this?

When

If you want an object to be really loaded when you first access a method of it , use proxy.

The object will be loaded when getValue is accessed (not 100% sure of it, but should be true).

I've never used it in real life but with collection. Lazy loading of collection is enabled by in collection mapping. No need for proxy parameter.

How
is the easiest way. Your class should not be final.
For collection add in collection mapping.

To sumarize, don't bother with proxy parameter.

In essence, a proxy is to single-point associations what lazy is to collection associations. It is simply a way to defer loading an associated object until it is needed (if ever).

For proxies, Hibernate dynamically generates a class which represents your object. It follows the interceptor type pattern. When you access an attribute of the proxied class (other than the id), the Hibernate-generated proxy will load the underlying data from the database. It is somewhat akin to the java notion of proxy (java.lang.reflect.Proxy).

so where do you guys use proxys in apps?

I cant seem to think of a usecase where I would need to use it (yet), if I load the object its because I need to use it immediately

Every single one of my domain entities has a Hibernate proxy defined for it. So I use it all over the place.

Without using proxies, all many-to-one associations will be loaded as soon as the association owner is loaded.

Also, say a user on a web screen chooses som drop-down value as part of a form. In processing that form, you need to set an association on some class based on selected id value from the drop down. So, you'd have to do something like:


Without the use of proxies, the above statements would cause two select statements, plus the update statement at flush time. If you utilize proxies, Hibernate can skip loading the OwnedAssociation class...

would it be safe to say I should always use proxys in a web-enviroment?

Depends the query done whth your objects. Here is an example of lazy loading overhead


You'll have 2 queries instead of 1.

As steve points out, association updates, used by web forms update use cases, are optimized with lazy loading.

FWIW,
You would have 2 queries there regardless of proxy usage/non-usage.

For a description of proxies, go to the Documentation tab, under Hibernate2 Documentation. In the Hibernate2 Reference Manual. There is a description of Proxies in section 11.1.

Despite usage of outer join ?

outer-join just tells Hibernate to go ahead on initialize the association even if there is a proxied assocation. So yeah.

outer-join="true" means use an outer join, regardless of proxies
outer-join="false" means never use an outer join, regardless of proxies
outer-join="auto" means use an outer join, unless there is a proxy