How to use JPA/JTA in a (CDI) Bean and in a outside way

Question

I have a JSF application (Java 8, Wildfly 10, MySQL DB, CDI beans, use of JPA). I got my EntityManager from a self-made static JpaHelper class, it also contains frequently used queries. Everything worked fine, but the amount of MySQL connection exhausted.

I switched to a wildfly managed connection to the database. Now my problems started. Now I inject EntityManager in my beans by:

package controller;

import ...

@ViewScoped
@Named
public class ListCommoditiesController implements Serializable {
    private static final long serialVersionUID = 4593863260881355166L;
    private int commodityId = 0;
    @PersistenceContext(unitName = "PU", type = PersistenceContextType.EXTENDED)
    private EntityManager em;

    public ListCommoditiesController() {

    }

    @SuppressWarnings("unchecked")
    public List<Commodity> getCommodities() {
        List<Commodity> commodities = (List<Commodity>) em.createNamedQuery("Commodity.findAll").getResultList();

        return commodities;
    }

and switched most of the frequently used queries to namedQueries. Some POJOs, Converter and Helper Classes still use my static JpaHelper, because I cannot inject the EM in there and cannot pass the information before, ie in a JSF converter class:

@Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
    if (value.isEmpty()) {
        return null;
    }
    Integer id = new Integer(value);
    return JpaHelper.getCommodityByID(id);
    }
}

If I use

<persistence-unit name="PU" transaction-type="RESOURCE_LOCAL">

I got an error "Transaction is required to perform this operation (either use a transaction or extended persistence context" in my CDI-Beans. There are recommendations to avoid the use of resource_local. But If I use

<persistence-unit name="PU" transaction-type="JTA">

I got an error "Unable to access TransactionManager or UserTransaction to make physical transaction delegate" in my JpaHelper class while creating the EntityManager.

My JpaHelper looks like:

public class JpaHelper {
private static final String PERSISTENCE_UNIT_NAME = "PU";

static public EntityManager getEntityManager() {
    EntityManagerFactory fact = Persistence.createEntityManagerFactory(
            JpaHelper.PERSISTENCE_UNIT_NAME);

    return fact.createEntityManager();
}

public static Commodity getCommodityByID(Integer id) {
    if (id != null) {
        EntityManager em = JpaHelper.getEntityManager();
        try {
            return (Commodity) em.find(Commodity.class, id);
        } catch (Throwable ex) {
            ex.printStackTrace();
        } finally {
            em.close();
        }
    }
    return null;
}

My persistence.xml looks like:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
    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_2_0.xsd">
    <persistence-unit name="PU" transaction-type="JTA">
        <jta-data-source>java:jboss/datasources/Hanse</jta-data-source>
        <class>model.Commodity</class>
        <class>model....</class>
        <class>model....</class>
        <properties>
            <!-- <property name="hibernate.transaction.jta.platform" value="org.hibernate.service.jta.platform.internal.JBossAppServerJtaPlatform"/> -->
            <!-- <property name="hibernate.hbm2ddl.auto" value="update" /> -->
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect" />
            <!-- <property name="hibernate.show_sql" value="true" /> -->
            <property name="hibernate.enable_lazy_load_no_trans" value="true"/>
        </properties>
    </persistence-unit>
</persistence>

I found out, that there are different strategies like container managed transaction, bean managed transaction and application managed transaction. But I think, I messed up things. How can I create an EntityManager (without injecting/in a not-bean class) with JTA? If I found a solution for one thing, it breaks my code on an other side. Am I on the right way or are the fundamental mistakes in the proceeding?

You should inject `EntityManager` in your `CDI` beans and inject these beans in JSF Managed Beans where you need them (for JSF converter you can use [this](http://stackoverflow.com/questions/7665673/how-to-inject-ejb-persistencecontext-inject-autowired-etc-in-facesconve)) — Geinmachi, Aug 14 '16 at 09:49
As mentioned above the injection of EntityManager in the CDI beans is no problem, it works fine. I will have a look to the solution of the link, but nevertheless I still have JPA access beyond CDI beans and Converter classes (perhaps it was a bad example). — xentity, Aug 14 '16 at 10:17
@BalusC Thx, but Am I able to use the EJB-Annotation in POJOs, ie. JPA Entities, also? I understood I just can use it in beans?! My questiion is, how to get access to EntityManager, if the calling class is no bean? — xentity, Aug 14 '16 at 11:24
There's too much wrong you basically need a book as answer. You need to restart from scratch to grasp the correct concepts. Just follow the guidelines in the duplicate and check all links therein for more examples and in depth explanation. If you have a more specific question which isn't covered in the duplicate, feel free to ask a new question. — BalusC, Aug 14 '16 at 11:31

How to use JPA/JTA in a (CDI) Bean and in a outside way

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