...

The Intro page provides an overview, the setup of this module and describes the motivation for the features described below. This page explains the most important APIs and mechanisms of the JPA module provided by CODI. Please note that this page doesn't show all possibilities. If you have any question, please contact the community!

Using one (default) Entity Manager

The following example will create a CDI producer method for creating a @RequestScoped EntityManager with qualifier @Default.

public class DataBaseProducer
{
    @Produces
    @PersistenceContext(unitName="default")
    private EntityManager entityManager;

    @Produces
    @Default
     private@RequestScoped
    public EntityManager createDefaultEntityManager()
    {
        return this.entityManager;
    }

    public void dispose(@Disposes @Default EntityManager entityManager)
    {
        if(entityManager.isOpen())
        {
            entityManager.close();
        }
    }
}

...

//...
public class CustomService1
{
    @Inject
    protected EntityManager entityManager;

    @Transactional
    public void update(CustomEntity1 entity)
    {
        this.entityManager.merge(entity);
    }
}

...

public class DataBaseProducer
{
    @PersistenceContext(unitName="default")
    private @ProducesEntityManager entityManager;

    @PersistenceContext(unitName="defaultUserDB")
    private EntityManager usersEntityManager;

    @Produces
    @Default
    privatepublic EntityManager createDefaultEntityManager()
    {
        return this.entityManager;
    }

    @Produces
    @Users
  @PersistenceContext(unitName="UserDB"  public EntityManager createUsersEntityManager()
    @Users{
       private EntityManagerreturn this.usersEntityManager;
    }

    public void disposeDefaultDB(@Disposes @Default EntityManager entityManager)
    {
        if(entityManager.isOpen())
        {
            entityManager.close();
        }
    }

    public void disposeUserDB(@Disposes @Users EntityManager entityManager)
    {
        if(entityManager.isOpen())
        {
            entityManager.close();
        }
    }
}

//...
public class CustomService2
{
    @Inject
    @Users
    protected EntityManager entityManager;

    @Transactional(Users.class)
    public void update(CustomEntity2 entity)
    {
        this.entityManager.merge(entity);
    }
}

EntityManager injection without producer (CODI v1.0.3+)

//...
public class CustomService3
{
    @PersistenceContext(unitName = "default")
    private EntityManager entityManager;

    @Transactional
    public void delete(Entity entity)
    {
        this.entityManager.remove(em.merge(entity));
    }

    @PreDestroy
    public void cleanup()
    {
        if(this.entityManager.isOpen())
        {
            this.entityManager.close();
        }
    }
} 

...

Extended Persistence Contexts

...

This approach just works if it doesn't come to serialization of this wrapper e.g. in case of session-replication.
If those beans get serialized, you have to overcome this restriction by storing the persistence-unit-name and recreate the EntityManager via Persistence.createEntityManagerFactory(this.persistenceUnitName).createEntityManager(); btw. sync it with the database before closing it on serialization. Furthermore, you have to intercept some methods of the EntityManager to merge detached entities automatically if those entities get serialized as well. However, as mentioned before we don't recommend such an approach.

JTA

CODI itself doesn't support it, but JTA support is available in Apache DeltaSpike.
Currently there is no support for it, however, you can use https://github.com/openknowledge/openknowledge-cdi-extensions in combination with MyFaces CODI for using JTA (if it works in combination with the application server of your choice).

TransactionScoped (since v1.0.2)

The @Transactional annotation of Apache MyFaces CODI will maintain an own transcaction context which automatically starts when an @Transactional method gets invoked, and ends when the outermost @Transactional method returns. This might for example be used to create @TransactionScoped EntityManagers. The effect of such an EntityManager is similar to using EJBs: when the outermost @Transactional method returns, the @TransactionScoped EntityManager will get destroyed and thus em.close() will get called effectively detaching all entities.

This scope is esp. useful if the loaded entities have to be cached.

public class DataBaseProducer
{
    @PersistenceContext(unitName="default")
    private EntityManager entityManager;

    @Produces
    @TransactionScoped
    public EntityManager createEntityManager()
    {
        return this.entityManager;
    }

    public void dispose(@Disposes EntityManager entityManager)
    {
        if(entityManager.isOpen())
        {
            entityManager.close();
        }
    }
}

ConfigurableDataSource (since v1.0.2)

Configuring the data connection properties in JPA projects in pure Java EE is always a painful task. Directly configuring the JDBC driver class and database credentials in the persistence.xml is a no-go.
Configuring a DataSource via JNDI sounds good at the first glance, but has serious flaws:

• providing JNDI for native unit tests (without starting the EE container) requires a lot of tweaking.
• JNDI locations for configured DataSources are not specified. Configuring the same myDb DataSource in n EE containers will give you n different JNDI locations - thus it's not possible to use a fixed JNDI location in your persistence.xml

A solution to this problem is provided via the Apache MyFaces CODI ConfigurableDataSource. This is a thin DataSource wrapper which will get it's configuration via CDI mechanics.

<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
    version="1.0">

    <persistence-unit name="test" >
        <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>

        <class>org.apache.myfaces.extensions.cdi.jpa.test.TestEntity</class>

        <properties>
            <property name="openjpa.jdbc.DBDictionary" value="hsql" />
            <property name="openjpa.ConnectionDriverName"
             value="org.apache.myfaces.extensions.cdi.jpa.impl.datasource.ConfigurableDataSource"/>
            <property name="openjpa.ConnectionProperties" value="connectionId=core"/>
        </properties>
    </persistence-unit>
</persistence>

The configuration itself is provided by implementing the CODI DataSourceConfig class. The DataSourceConfig determines whether a JNDI path, a JDBC connection or another DataSource should get used, by just returning the proper values. You can use all the flexible CDI and CODI mechanisms like @ProjectStageActivated, @ExpressionActivated, @Alternative, @Specializes, etc and even if/then/else,... to find the perfect settings for your current runtime environment!

TransactionHelper

This helper allows to execute CDI-unmanaged code blocks in a @Transactional manner. E.g. with the test modules provided by MyFaces CODI you can inject CDI beans and therefore transactional services into a JUnit test. So it's possible to use existing implementations e.g. to create sample data for unit tests or to remove such entries again. If a service doesn't (or shouldn't) provide the needed functionality e.g. for deleting entities, it's possible to use TransactionHelper for such additional logic which should be executed within a transaction.

MyReslt result = TransactionHelper.getInstance().executeTransactional(new Callable<MyReslt>() {
    public MyReslt call() throws Exception
    {
        EntityManager entityManager = BeanManagerProvider.getInstance().getContextualReference(EntityManager.class);
        entityManager.remove(...);
        return entityManager.find(...);
    }
});