[FIXED] Servlet does not persist an Entity

Issue

What do I want to do:

I just started with JPA and therefore i want to understand how persisting Entitys from different perspectives work (Application-Managed, Container-Managed). Application-Managed works fine, however i have problems persisting an Entity with an Entity Manager from within a Web Application using a TestServlet.

What have I done so far:

IDE: NetBeans 8.0.2 Server: GlassFish 4.1 Mysql 5.6 JPA 2.1: EclipseLink

1. I've created a Web Application Project.
2. I've imported the Entitys from the Database using the NetBeans Wizard. For some reason I am not able to import them from jdbc/__default. I have to create a new Data Source. In this case it was jdbc/__onlineshop

I simply want to create an Entity within a Servlet and persist it in the database just to understand how it works before I move on but apparently I don't quite get it.

I am connected to the database and i can access it via a Java-Application but not using a Servlet from a Web-Container.

The MySQL Driver is in the classpath MAIN - Libraries.

No Exceptions are thrown. The Servlet is called which I am able to see in the browser. However the redirection through the RequestDispatcher does not work either, the browsers URL stays at web-jpa/test.

My Question:

Is there anything wrong with my Servlet or the persistence.xml since persisting does not work ?

persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/ persistence" 
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence 
         http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">

<persistence-unit name="jpa-webPU" transaction-type="JTA">
 <jta-data-source>jdbc/__onlineshop</jta-data-source>
 <exclude-unlisted-classes>false</exclude-unlisted-classes>
 <properties/>
</persistence-unit>

TestServlet.java :

package jpa;

import java.io.IOException;
import javax.annotation.Resource;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceUnit;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.transaction.UserTransaction;

@WebServlet("/test")
public class TestServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;


@PersistenceUnit
EntityManagerFactory emf;

@Resource
private UserTransaction ut;

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {


    EntityManager em = emf.createEntityManager();

    Customer customer = new Customer();

    customer.setEmail("[email protected]");
    customer.setPassword("password");

    try 
    {
        ut.begin();
        em.persist(customer);
        ut.commit();

    } catch (Exception e) {

        try 
        {
            ut.rollback();

        } catch (Exception e1) 
        {
            e1.printStackTrace();
        }

        throw new ServletException(e.getMessage());

    }finally
    {
        em.close();
    }

    RequestDispatcher dispatcher = request.getRequestDispatcher    ("index.html");
    dispatcher.forward(request, response);

}
}

Thank you !

p.s.: Any Hint is appreciated !

Solution

Finally I have found a solution:

try
{
  ut.begin();
  em.joinTransaction(); // this is necessary, the entitymanager needs to be called specifically
  em.persist(customer);
  ut.commit();
}

Answered By - SklogW
Answer Checked By - David Goodson (JavaFixing Volunteer)