How to inject EntityManager via Eclipselink?

[Stephan Wöbbeking]

Hi *,

I am currently struggling as I can't get all the details together. I do have a working database (Derby, coming with jdk1.8.0_141) and a running TomCat (apache-tomcat-8.5.23) on top. For the JPA I use EclipseLink (eclipselink-2.7.0.v20170811-d680af5). The general access to the database works fine, this is how I get the EntityManager:

private static EntityManager em = Persistence.createEntityManagerFactory( "cotu" ).createEntityManager();

This is my persistence.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<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"
	version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
	<persistence-unit name="cotu">
		<jta-data-source>java:comp/DefaultDataSource</jta-data-source>
		<class>swsoft.games.cotu.user.GameUser</class>
... more classes
		<class>swsoft.games.cotu.model.Universe</class>
		<properties>
			<property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.ClientDriver" />
			<property name="javax.persistence.jdbc.url"
				value="jdbc:derby://localhost:1527/C:/Users/049SWoebbeking/DataSource/JavaDB/CotU_1;create=true" />
			<property name="javax.persistence.jdbc.user" value="test" />
			<property name="javax.persistence.jdbc.password" value="test" />

			<!-- EclipseLink should create the database schema automatically
					create newly: drop-and-create-tables -->
			<property name="eclipselink.ddl-generation" value="create-or-extend-tables" />
			<property name="eclipselink.ddl-generation.output-mode" value="database" />
		</properties>
	</persistence-unit>
</persistence>

Now I tried to have the EntityManager being injected like this:

	@PersistenceContext
    private static EntityManager em2;

Of course I have modified the persistence.xml in various ways, but I couldn't get it to work. The EntityManager "em2" is always null!

Can anyone tell me, what I am missing here? Thanks a lot guys!
Stephan

[Frits Walraven]

In what kind of EE - component are you injecting the EntityManager ( EJB, Servlet, CDI bean )?

[Stephan Wöbbeking]

Frits Walraven wrote:In what kind of EE - component are you injecting the EntityManager ( EJB, Servlet, CDI bean )?

Good point! I was playing around with it a little bit. I tried @Stateful and @EJB. The class is marked as @ManagedBean, @SessionScoped, @Entity as well... The number of combinations between different annotations and choices for naming in the persistence.xml is to high, I just wasn't able to try it all. So I need less trial and error and more knowledge. ;))

Stephan

[Stephan Wöbbeking]

It never occured to me that tomcat maybe could NOT be a valid JEE container, is it???

Stephan

[Frits Walraven]

Tomcat only consists of a web-container (no ejb-container).

[Stephan Wöbbeking]

Ok, I guess that's the point in it... Don't know why it never occured to me...
Thanks anyway, now I will keep on struggling with TomEE configuration, but that's a different story,
Stephan