jakarta ee - eclipselink does not generate tables from annotated JPA classes

Question

My IDE is eclipse -Helios and I am using mojarra jsf, mysql, eclipselink for jpa.

In my project, if I create the tables manually in mysql, I can see those tables in the "JPA Details" view. And if I don't create any table, the eclipse IDE shows an error, "Table "trainingsession" cannot be resolved".

I am not sure what's wrong. When would JPA create these tables ? and how ? my persistence.xml is as follows,

<?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="wompower2" transaction-type="RESOURCE_LOCAL">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <jta-data-source>trainer</jta-data-source>
    <class>com.jsfcompref.trainer.entity.User</class>
    <class>com.jsfcompref.trainer.entity.TrainingSession</class>
    <class>com.jsfcompref.trainer.entity.Event</class>
    <class>com.jsfcompref.trainer.entity.AbstractEntity</class>
    <validation-mode>NONE</validation-mode>
    <properties>
      <property name="eclipselink.target-database" value="MySQL"/>
      <property name="eclipselink.ddl-generation" value="create-tables"/>
      <property name="eclipselink.ddl-generation.output-mode" value="both"/>
      <property name="eclipselink.application-location" value="C:wompower2DDL"/>
      <property name="eclipselink.create-ddl-jdbc-file-name" value="create.sql"/>
      <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/demo"></property>
      <property name="javax.persistence.jdbc.user" value="user"></property>
      <property name="javax.persistence.jdbc.password" value="pwd"></property>
      <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"></property>
    </properties>
  </persistence-unit>
</persistence>

Thank you, Arindam.

Answer 1

First let me clarify that JPA is a standard spec for ORM and EclipseLink is one of the implementor of the spec (Hibernate is another example). The spec doesn't mandate the creation of the schema or tables though EclipseLink provides a mechanism to create the tables for you through configuration. Below are the two config properties controlling that

<property name="eclipselink.ddl-generation" value="create-tables" />
<property name="eclipselink.ddl-generation.output-mode" value="database" />

Go through this tutorial for more information (specifically 3.2 section)