Hi,

Is it possible to retrieve the 'EJB3' metadata of an entity?

Using Hibernate this is possible by using:


I'm wondering if this is also possible within the EJB3 specs?


Cheers,
Marcel

Can't you just use reflection?

Class xyz;
Entity entity = xyz.getAnnotation(Entity);

That sort of thing? Or am I missing the point?

I like to retrieve more than only field names.

I like to get the field names, field types, field lengths etc.

With the getAnnotation I cannot get the fields at all because you don't need to annotate them.

Any help on this appreciated.

To be more precise:
I actually like to know alle database column information associated with a class.

If you don't annotate them then they will be using the defaults, won't they?

But only annotations is not enough. You could use reflection to get all the methods of the entity bean but you have to some plumbing yourself to find out if it's a field or relationship or whatever.

Bill Burke mentioned something in a old post:
http://jboss.org/jbossBlog/blog/?month=7&year=2004
The entity bean deployer iterates all get/set methods to determine the persistent fields. Properties that have a generic Collection type of a different entity bean are treated as one-to-many relationships by default.

This is what I'm looking for togehter wit annotation you also can find out the length, nullable etc of the fields.

There is not EJB3 standard way, but you can still use the Hibernate getMetadata solution

Is it possible to get the SessionFactory without having any hibernate mapping files. I'm using only Java 5 annotations for my enitity beans.

if you want true database properties (nullable, length etc) you have to use pure jdbc DatabaseMetadata - hibernate mapping (hbm or annotations) haven't to set length , nullable or it can be different from database
for example, length is hint for hibernate for schema export - true length is in database only

I can use the Column annotation attributes length and nullable for this.
If not filled inm I can always use a default setting like length = 50, optional = true.

But I was thinking about how to identify which field/getMethods are related to an column, and to get the type.

You could for example have a String as return type of a method, but also have proprietary class which is in fact also a String.
Also the class has methods inherited from java.lang.Object which are not related to columns, but just to the Java language.

sure
( (HibernateEntityManagerFactory) emf).getSessionFactory()