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Java Hibernate Basics Persisting Data with Hibernate Saving Data with Hibernate

shekhar bhardwaj
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shekhar bhardwaj
Full Stack JavaScript Techdegree Student 12,373 Points

Error: Exception in thread "main" org.hibernate.MappingException: Unknown entity: com.hibernate.demo.model.Contact

NEED HELP !!!

My hibernate.cfg.xml :-

<?xml version='1.0' encoding='utf-8'?>

<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <!-- Database connection settings -->
        <property name="connection.driver_class">org.h2.Driver</property>
        <property name="connection.url">jdbc:h2:./data/contactmgr</property>


        <property name="connection.username">sa</property>


        <property name="hibernate.default_schema">PUBLIC</property>

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.H2Dialect</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>

        <!-- Drop and re-create the database schema on startup -->
        <property name="hbm2ddl.auto">create</property>

        <property name="show_sql">true</property>

        <mapping class="com.hibernate.demo.model.Contact"/>

    </session-factory>

</hibernate-configuration>

my Application.java Main class :-

package com.contact;



import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.FileLock;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;

import com.contact.model.Contact;

public class Application {

    //Session factory
    private static final SessionFactory sessionFactory = buildSesssionFactory();

    public static void main(String[] args) throws InterruptedException {

        System.out.println("Session factory");
        Contact contact = new Contact.ContactBuilder("Bob", "Marley").withEmail("bob.nik@gmail.com").withPhone(5859789733L).build();

        //Open a Session
        System.out.println("Open a Session");
        Session session = sessionFactory.openSession();

        //Begin a Transaction
        System.out.println("Begin a Transaction");
         session.beginTransaction();


        //Use the session to save the contact
        System.out.println("Use the session to save the contact");
        session.save(contact);
        //Commit the transaction
        System.out.println("Commit the transaction");
        session.getTransaction().commit();
        // Close the session
        System.out.println("Close the session");
        session.close();
    }

    private static SessionFactory buildSesssionFactory() {
        // Create a StandardServiceRegistry
        Configuration configuration = new Configuration();
        configuration.addAnnotatedClass(com.contact.model.Contact.class);
        configuration.setProperty("hibernate.temp.use_jdbc_metadata_defaults","false");
        configuration.configure();

        final ServiceRegistry registry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
        return new org.hibernate.boot.MetadataSources(registry).buildMetadata().buildSessionFactory();


    }

    static boolean isLocked(String fileName) {
        try {
            RandomAccessFile f = new RandomAccessFile(fileName, "r");
            try {
                FileLock lock = f.getChannel().tryLock(0, Long.MAX_VALUE, true);
                if (lock != null) {
                    lock.release();
                    return false;
                }
            } finally {
                f.close();
            }
        } catch (IOException e) {
            // ignore
        }
        return true;
    }

}

Eception thrown : Exception in thread "main" org.hibernate.MappingException: Unknown entity: com.contact.model.Contact at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:776) at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1533) at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:104) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:192) at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:38) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:177) at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:32) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73) at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:682) at org.hibernate.internal.SessionImpl.save(SessionImpl.java:674) at org.hibernate.internal.SessionImpl.save(SessionImpl.java:669) at com.contact.Application.main(Application.java:38)

Need help !!!!!!!

2 Answers

Jeremiah Shore
Jeremiah Shore
31,168 Points

Can you edit your post to share your Contact class? May also help to use markdown on the exception message for readability.

Edward campbell malan van wyk
Edward campbell malan van wyk
6,403 Points

For anyone struggling with this, I fixed it by adding the following to my hibernat.cfg.xml file.

<mapping class="com.teamtreehouse.contactmgr.model.Contact"/>

To get your correct path right click on the

Contact.java

class and click copy reference and paste it in.