How to auto-register entities with JPA/Hibernate: Unknown entity

hibernate, java, jpa

Solution

It turned out to be fairly simple: list the classes directly in the persistence.xml file. Both armandino and MikelRascher led me to this answer, though indirectly, so props to them.

Here is the persistence.xml I'm using now:

<?xml version="1.0" encoding="UTF-8"?>
<persistence 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"
             version="1.0">

    <persistence-unit name="crm">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>

        <class>com.example.Language</class>

        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
            <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
            <property name="hibernate.connection.url" value="jdbc:mysql://localhost/crm"/>
            <property name="hibernate.connection.username" value="myuser"/>
            <property name="hibernate.connection.password" value="mypass"/>
            <property name="hibernate.c3p0.min_size" value="5"/>
            <property name="hibernate.c3p0.max_size" value="20"/>
            <property name="hibernate.c3p0.idleTestPeriod" value="30"/>
            <property name="hibernate.c3p0.timeout" value="0"/>
            <property name="hibernate.c3p0.max_statements" value="0"/>
            <!--property name="hibernate.show_sql" value="true"/>-->
            <property name="hibernate.format_sql" value="true"/>
            <property name="hibernate.query.jpaql_strict_compliance" value="false"/>
            <property name="hibernate.validator.apply_to_ddl" value="false"/>
            <property name="hibernate.validator.autoregister_listeners" value="false"/>
            <property name="hibernate.archive.autodetection" value="class, hbm"/>
            <property name="hibernate.hbm2ddl.auto" value="create"/>
        </properties>
    </persistence-unit>

</persistence>

Problem

I'm stumped with a Hibernate/JPA configuration issue that's preventing my JPA-annotated entities from being automatically registered: ``` java.lang.IllegalArgumentException: Unknown entity: com.example.crm.server.model.Language at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:671) at com.example.crm.server.model.Language.persist(Language.java:64) at com.example.crm.server.LanguageTest.testPersistAndRemove(LanguageTest.java:32) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) ``` In my entity class I have: ``` @Entity @Table(name="Languages") public class Language implements Serializable { @Id private Long id; private String name; // etc... } ``` And in MySQL, the Languages table looks like: ``` +-------------+----------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+----------+------+-----+---------+-------+ | Language_ID | int(11) | NO | PRI | NULL | | | Name | char(18) | YES | | NULL | | +-------------+----------+------+-----+---------+-------+ 2 rows in set (0.00 sec) ``` And my persistence.xml looks like: ``` <?xml version="1.0" encoding="UTF-8"?> <persistence 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" version="1.0"> <persistence-unit name="crm"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/> <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/> <property name="hibernate.connection.url" value="jdbc:mysql://localhost/crm"/> <property name="hibernate.connection.username" value="crmuser"/> <property name="hibernate.connection.password" value="mypass"/> <property name="hibernate.c3p0.min_size" value="5"/> <property name="hibernate.c3p0.max_size" value="20"/> <property name="hibernate.c3p0.idleTestPeriod" value="30"/> <property name="hibernate.c3p0.timeout" value="0"/> <property name="hibernate.c3p0.max_statements" value="0"/> <property name="hibernate.format_sql" value="true"/> <property name="hibernate.query.jpaql_strict_compliance" value="false"/> <property name="hibernate.validator.apply_to_ddl" value="false"/> <property name="hibernate.validator.autoregister_listeners" value="false"/> <property name="hibernate.archive.autodetection" value="class, hbm"/> <property name="hibernate.hbm2ddl.auto" value="create"/> </properties> </persistence-unit> </persistence> ``` EDIT: here's how I'm getting my EntityManager and persisting: ``` public void persist() { EntityManager em = entityManager(); try { em.getTransaction().begin(); em.persist(this); em.getTransaction().commit(); } finally { em.close(); } } public static EntityManager entityManager() { return EMF.get().createEntityManager(); } ```

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