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POJPA entries are not created or retrieved
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  1. POJPA entries are not created or retrieved
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    copied!<p>I'm having program that creates JPA entries with the entity manager. during the process I <strong>don't get any errors</strong>.</p> <pre><code>... factory = Persistence.createEntityManagerFactory("perst"); EntityManager entityManager = factory.createEntityManager(); entityManager.getTransaction().begin(); entityManager.persist(object); entityManager.getTransaction().commit(); ... entityManager.close(); </code></pre> <p>I have created a program like follows to read the data but it doesn't return any data, the query returns empty. What could be the reason ?</p> <p>This is the program to read the data:</p> <pre><code>static List&lt;String&gt; classList = new ArrayList&lt;String&gt;(); private static EntityManagerFactory factory; public static void main(String[] args) { // TODO Auto-generated method stub factory = Persistence.createEntityManagerFactory("perst"); EntityManager entityManager = factory.createEntityManager(); classList.add("LeaveRequest"); classList.add("person"); for (Object classOjc : classList) { String className = classOjc.toString(); Query query = entityManager.createQuery("SELECT p FROM " + className + " p"); @SuppressWarnings("rawtypes") List resultList = query.getResultList(); System.out.println(resultList.size()); for (Object result : resultList) { System.out.println(result.toString()); } } } </code></pre> <p>the xml persist is:</p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;persistence version="1.0" 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_1_0.xsd"&gt; &lt;persistence-unit name="perst" transaction-type="RESOURCE_LOCAL"&gt; &lt;provider&gt;org.eclipse.persistence.jpa.PersistenceProvider&lt;/provider&gt; &lt;class&gt;LeaveRequest&lt;/class&gt; &lt;class&gt;person&lt;/class&gt; &lt;properties&gt; &lt;property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.EmbeddedDriver" /&gt; &lt;property name="javax.persistence.jdbc.url" value="jdbc:derby:/home/vogella/databases/simpleDb;create=true" /&gt; &lt;property name="javax.persistence.jdbc.user" value="Sales" /&gt; &lt;property name="javax.persistence.jdbc.password" value="" /&gt; &lt;!-- EclipseLink should create the database schema automatically --&gt; &lt;property name="eclipselink.ddl-generation" value="drop-and-create-tables" /&gt; &lt;property name="eclipselink.ddl-generation.output-mode" value="database" /&gt; &lt;property name="eclipselink.logging.level" value="SEVERE" /&gt; &lt;property name="eclipselink.logging.exceptions" value="true" /&gt; &lt;/properties&gt; &lt;/persistence-unit&gt; &lt;/persistence&gt; </code></pre>
 

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