List the entity of a project

[jeremi]

Hi,
I'm writing an add-on to monitor entities of a roo project.

To do this, I'd like to be able to list all the entity class and be able to execute query on them suing the persistence API.
My code would live in a controller (at least at the beginning). Is there an API to do this?

Thanks,
Jeremi

[jeremi]

Using the petstore demo, I'm doing :

            resp.put("Owner", Owner.countOwners());
            resp.put("Pet", Pet.countPets());
            resp.put("Vet", Vet.countVets());
            resp.put("Visit", Visit.countVisits());
        }

but I would like to be able to do something more like:

        entities = magicFunctionToFind();
        for (Object entity : entities) {
            resp.put(entity.getClass().getName(), entity.count...());        
        }

I need to find the magicFunctionToFind to give me the list of entities in this project. Does this function exist?

[Andrew Swan]

Good question; it got me digging. If you're using JPA 2, you should be able to find out the managed entities via the Metamodel API.

I'm still trying to figure out if it's possible with JPA 1. It might depend on what JPA provider you are using. Maybe there's a vendor specific API that you can access by casting the injected JPA EntityManager to its vendor-specific implementation.

Latest update: if you're using a recent enough version of Hibernate and can get hold of the org.hibernate.ejb.EntityManagerFactoryImpl (maybe by casting an injected javax.persistence.EntityManagerFactory?), you can call getSessionFactory().getAllClassMetadata() to find out the entity classes.

Please let us know if this works.

[jeremi]

Great Thanks!

If anyone is interested by the solution, add to the class:

   @PersistenceContext
    EntityManager entityManager;

And you can do:

             Metamodel metamodel = entityManager.getMetamodel();

            for (EntityType entityType : metamodel.getEntities()) {
                System.out.println("-------->>>>" + entityType.getName());
            }

[Andrew Swan]

Nice. So what version of Roo and JPA are you using? In Roo 1.0.2 with JPA declared thus:

<dependency>
    <groupId>javax.persistence</groupId>
    <artifactId>com.springsource.javax.persistence</artifactId>
    <version>1.0.0</version>
</dependency>

... there's no method called EntityManager#getMetamodel().

[jeremi]

I like to live on the edge I'm using roo 1.1.0.M1.

I think

com.springsource.javax.persistence

has been replaced by

org.hibernate.javax.persistence

    <dependency>
            <groupId>org.hibernate.javax.persistence</groupId>
            <artifactId>hibernate-jpa-2.0-api</artifactId>
            <version>1.0.0.Final</version>
        </dependency>
    <dependency>