org.hibernate.MappingException: Unknown entity

Question

I'm trying to work through Beginning Hibernate 2nd edition, and I'm stuck trying to put together the simple working example with HSQLDB.

When I run ant populateMessages, I get

[java] org.hibernate.MappingException: Unknown entity: sample.entity.Message
[java]     at org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:194)
[java]     at org.apache.tools.ant.taskdefs.Java.run(Java.java:747)
...

Here's what I've got:

Message.java

package sample.entity;

import org.hibernate.annotations.Entity;

import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
public class Message
{
    private String messageText;
    private Integer id;

    public Message( String messageText )
    {
        this.messageText = messageText;
    }

    public Message()
    {
    }

    public String getMessageText()
    {
        return messageText;
    }

    public void setMessageText(String messageText)
    {
        this.messageText = messageText;
    }

    @Id
    @GeneratedValue
    public Integer getId()
    {
        return id;
    }

    public void setId(Integer id)
    {
        this.id = id;
    }
}

PopulateMessages.java

package sample;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;
import sample.entity.Message;

import java.util.Date;

public class PopulateMessages
{
    public static void main(String[] args)
    {
        SessionFactory factory = new AnnotationConfiguration().configure().buildSessionFactory();
        Session session = factory.openSession();
        session.beginTransaction();

        Message m1 = new Message("Hibernated a  messages on " + new Date());
        session.save(m1);
        session.getTransaction().commit();
        session.close();
    }
}

build.properties

# Path to the hibernate install directory
hibernate.home=C:/hibernate/hibernate-3.5.6
# Path to the hibernate-tools install directory
hibernate.tools.home=C:/hibernate/hibernate-tools
# Path to hibernate-tools.jar relative to hibernate.tools.home
hibernate.tools.path=/plugins/org.hibernate.eclipse_3.3.1.v201006011046R-H111-GA/lib/tools
# Path to hibernate-tools hibernate libraries relative to hibernate.tools.home
hibernate.tools.lib.path=/plugins/org.hibernate.eclipse_3.3.1.v201006011046R-H111-GA/lib/hibernate
# Path to the SLF4J implementation JAR for the logging framework to use
slf4j.implementation.jar=lib/slf4j-simple-1.6.1.jar
# Path to the HSQL DB install directory
hsql.home=C:/hsqldb

hibernate.cfg.xml

<!DOCTYPE hibernate-configuration PUBLIC
 "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.url">
jdbc:hsqldb:file:testdb;shutdown=true
</property>
<property name="hibernate.connection.driver_class">
org.hsqldb.jdbcDriver
</property>
<property name="hibernate.connection.username">sa</property>
<property name="hibernate.connection.password"></property>
<property name="hibernate.connection.pool_size">0</property>
<property name="hibernate.dialect">
org.hibernate.dialect.HSQLDialect
</property>
<property name="hibernate.show_sql">false</property>
<!-- "Import" the mapping resources here -->
<mapping class="sample.entity.Message"/>
</session-factory>
</hibernate-configuration>

build.xml

<project name="sample">
    <property file="build.properties"/>
    <property name="src" location="src"/>
    <property name="bin" location="bin"/>
    <property name="sql" location="sql"/>
    <property name="hibernate.tools"
              value="${hibernate.tools.home}${hibernate.tools.path}"/>
    <path id="classpath.base">
        <pathelement location="${src}"/>
        <pathelement location="${bin}"/>
        <pathelement location="${hibernate.home}/hibernate3.jar"/>
        <pathelement location="${slf4j.implementation.jar}"/>
        <fileset dir="${hibernate.home}/lib" includes="**/*.jar"/>
        <pathelement location="${hsql.home}/lib/hsqldb.jar"/>
  <fileset dir="./lib" includes="**/*.jar"/>
    </path>
<path id="classpath.tools">
    <path refid="classpath.base"/>
    <pathelement
            location="${hibernate.tools.home}/${hibernate.tools.lib.path}/commons-logging-1.0.4.jar"/>
    <pathelement
            location="${hibernate.tools}/freemarker.jar"/>
    <pathelement
            location="${hibernate.tools}/hibernate-tools.jar"/>
</path>
<taskdef name="htools"
         classname="org.hibernate.tool.ant.HibernateToolTask"
         classpathref="classpath.tools"/>
<target name="exportDDL" depends="compile">
    <mkdir dir="${sql}"/>
    <htools destdir="${sql}">
        <classpath refid="classpath.tools"/>
        <annotationconfiguration
                configurationfile="${src}/hibernate.cfg.xml"/>
        <hbm2ddl drop="true" outputfilename="sample.sql"/>
    </htools>
</target>
<target name="compile">
    <javac srcdir="${src}" destdir="${bin}" classpathref="classpath.base"/>
</target>
<target name="populateMessages" depends="compile">
    <java classname="sample.PopulateMessages" classpathref="classpath.base"/>
</target>
<target name="listMessages" depends="compile">
    <java classname="sample.ListMessages" classpathref="classpath.base"/>
</target>

+1 For the detailed question. I have encountered the same problem and and looking at your hibernate.cfg.xml showed me my problem. — apines
– apines, Commented Feb 28, 2014 at 12:19

Pascal Thivent · Accepted Answer · 2010-10-23 19:05:57Z

37

You entity is not correctly annotated, you must use the @javax.persistence.Entity annotation. You can use the Hibernate extension @org.hibernate.annotations.Entity to go beyond what JPA has to offer but the Hibernate annotation is not a replacement, it's a complement.

So change your code into:

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
public class Message { 
    ...  
}

References

Hibernate Annotations Reference Guide
- 2.4. Hibernate Annotation Extensions

answered Oct 23, 2010 at 19:05

Pascal Thivent

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5 Comments

Bozho Over a year ago

ah, the Note about Entity being mandatory is new to me (I've never used the hibernate annotation). I spotted that piece (see my update), but wasn't sure it is the answer :) (+1)

Pascal Thivent Over a year ago

@Bozho Can't say about the note but I'm sure that hibernate annotation has always been a complement, not a replacement. +1 for your update too then.

Stefan Kendall Over a year ago

I'll test. I never, ever would have caught this.

Pascal Thivent Over a year ago

@Stefan Well, that's a vicious issue and I detected it during an Nth scan of the code after chatting with Bozho. Actually, it's writing things that gave me an idea of what the problem could be.

zygimantus Over a year ago

But what if the required class that is an entity is from another library? Is there a way around using @Entity?

Bozho · Accepted Answer · 2013-03-03 07:07:57Z

12

You should call .addAnnotatedClass(Message.class) on your AnnotationConfiguration.

If you want your entities to be auto-discovered, use EntityManager (JPA)

(Reference)

Update: it appears you have listed the class in hibernate.cfg.xml. So auto-discovery is not necessary. Btw, try javax.persistence.Entity

edited Mar 3, 2013 at 7:07

answered Oct 23, 2010 at 6:28

Bozho

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6 Comments

Pascal Thivent Over a year ago

No, the OP shouldn't have to do that, the entity is declared in the hibernate.cfg.xml.

Bozho Over a year ago

@Pascal Thivent hmm, missed that line. Then it is strange, since by default the Configuration.configure() looks for hibernate.cfg.xml

Pascal Thivent Over a year ago

Yeah I agree, this is strange. I would expect things to fail totally (the .cfg.xml is not found), not "partially". Activating logging might help but I'm too lazy to set up an Ant build to reproduce :)

Pascal Thivent Over a year ago

LOL, I spotted the problem :)

Bozho Over a year ago

@Pascal Thivent and it is? :)

|

Saravana · Accepted Answer · 2016-09-10 17:06:37Z

1

In case if you get this exception in SpringBoot application even though the entities are annotated with Entity annotation, it might be due to the spring not aware of where to scan for entities

To explicitly specify the package, add below

@SpringBootApplication
@EntityScan({"model.package.name"})
public class SpringBootApp {...}

note: If you model classes resides in the same or sub packages of SpringBootApplication annotated class, no need to explicitly declare the EntityScan, by default it will scan

answered Sep 10, 2016 at 17:06

Saravana

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Comments

ErSyyedS · Accepted Answer · 2017-11-11 22:12:16Z

1

Use below line of code in the case of Spring Boot Application Add in Spring Boot Main Class @EntityScan(basePackageClasses=YourClassName.class)

answered Nov 11, 2017 at 22:12

ErSyyedS

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Comments

ErSyyedS · Accepted Answer · 2017-11-11 22:17:04Z

1

use below line of code in the case of spring boot applications.

@EntityScan(basePackageClasses=YourClassName.class)

answered Nov 11, 2017 at 22:17

ErSyyedS

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Comments

M.J. · Accepted Answer · 2010-10-23 07:10:45Z

0

you should add all the entity files in the .addAnnotatedClass(Class) method, if the class needs to be auto discovered.

use this link, it might help..

http://docs.jboss.org/hibernate/stable/core/api/org/hibernate/cfg/AnnotationConfiguration.html

answered Oct 23, 2010 at 7:10

M.J.

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Comments

Racil Hilan · Accepted Answer · 2015-10-04 23:09:47Z

0

I encountered the same problem when I switched to AnnotationSessionFactoryBean. I was using entity.hbm.xml before.

I found that My class was missing following annotation which resolved the issue in my case:

@Entity
@Table(name = "MyTestEntity")
@XmlRootElement

edited Oct 4, 2015 at 23:09

Racil Hilan

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answered Oct 4, 2015 at 22:45

Sanjay Ingole

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Comments

Akanksha · Accepted Answer · 2017-05-25 03:36:18Z

0

Use import javax.persistence.Entity; Instead of import org.hibernate.annotations.Entity;

answered May 25, 2017 at 3:36

Akanksha

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Comments

Santosh Reddy · Accepted Answer · 2019-02-09 12:18:10Z

0

My issue was resolved After adding
sessionFactory.setPackagesToScan( new String[] { "com.springhibernate.model" }); Tested this Functionality in spring boot latest version 2.1.2.

Full Method:

 @Bean( name="sessionFactoryConfig")
    public LocalSessionFactoryBean sessionFactoryConfig() {

        LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();

        sessionFactory.setDataSource(dataSourceConfig());
        sessionFactory.setPackagesToScan(
                new String[] { "com.springhibernate.model" });

        sessionFactory.setHibernateProperties(hibernatePropertiesConfig());

        return sessionFactory;
    }

answered Feb 9, 2019 at 12:18

Santosh Reddy

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Comments

Sachin Pawar · Accepted Answer · 2019-08-03 06:33:20Z

0

You can enable entity scan by adding below annotation on Application .java @EntityScan(basePackageClasses=YourEntityClassName.class)

Or you can set the packageToScan in your session factory. sessionFactory.setPackagesToScan(“com.all.entity”);

answered Aug 3, 2019 at 6:33

Sachin Pawar

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Comments

manikrishna · Accepted Answer · 2020-11-20 16:07:41Z

0

check that entity is defined in hibernate.cfg.xml or not.

answered Nov 20, 2020 at 16:07

manikrishna

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Comments

Satya Johnny · Accepted Answer · 2015-08-20 06:42:31Z

-2

In hibernate.cfg.xml , please put following code

<mapping class="class/bo name"/>

answered Aug 20, 2015 at 6:42

Satya Johnny

1

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