Hibernate : 엔티티 클래스를 기반으로 db 테이블 자동 생성 / 업데이트

Hibernate : 엔티티 클래스를 기반으로 db 테이블 자동 생성 / 업데이트

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다음 엔터티 클래스 (Groovy)가 있습니다.

import javax.persistence.Entity
import javax.persistence.Id
import javax.persistence.GeneratedValue
import javax.persistence.GenerationType

@Entity
public class ServerNode {

  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  Long id

  String firstName
  String lastName

}

내 persistence.xml :

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">
    <persistence-unit name="NewPersistenceUnit">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/Icarus"/>
            <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
            <property name="hibernate.connection.username" value="root"/>
            <property name="hibernate.connection.password" value=""/>
            <property name="hibernate.archive.autodetection" value="class"/>
            <property name="hibernate.show_sql" value="true"/>
            <property name="hibernate.format_sql" value="true"/>
            <property name="hbm2ddl.auto" value="create"/>
        </properties>
        <class>net.interaxia.icarus.data.models.ServerNode</class>
    </persistence-unit>
</persistence>

및 스크립트 :

import javax.persistence.EntityManager
import javax.persistence.EntityManagerFactory
import javax.persistence.Persistence
import net.interaxia.icarus.data.models.ServerNode

def factory = Persistence.createEntityManagerFactory("NewPersistenceUnit")
def manager = factory.createEntityManager()

manager.getTransaction().begin()

manager.persist new ServerNode(firstName: "Test", lastName: "Server")

manager.getTransaction().commit()

Icarus 데이터베이스 가 있지만 현재 테이블이 없습니다. Hibernate가 엔티티 클래스를 기반으로 테이블을 자동으로 생성 및 / 또는 업데이트하기를 바랍니다. 어떻게해야합니까?

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hibernate앞을 떠나는 것이 효과가 있는지 모르겠습니다 .

참조는 그것이 있어야 제안hibernate.hbm2ddl.auto

값은 createsessionFactory 생성시 테이블을 생성하고 그대로 둡니다.

값은 create-drop테이블을 만든 다음 sessionFactory를 닫을 때 삭제합니다.

javax.persistence.Table주석을 명시 적으로 설정해야 할까요?

도움이 되었기를 바랍니다.

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You might try changing this line in your persistence.xml from

<property name="hbm2ddl.auto" value="create"/>

to:

<property name="hibernate.hbm2ddl.auto" value="update"/>

This is supposed to maintain the schema to follow any changes you make to the Model each time you run the app.

Got this from JavaRanch

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Sometimes depending on how the configuration is set, the long form and the short form of the property tag can also make the difference.

e.g. if you have it like:

<property name="hibernate.hbm2ddl.auto" value="create"/>

try changing it to:

<property name="hibernate.hbm2ddl.auto">create</property>

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In my case table was not created for the first time without last property listed below:

<properties>
    <property name="hibernate.archive.autodetection" value="class"/>
    <property name="hibernate.show_sql" value="true"/>
    <property name="hibernate.format_sql" value="true"/>
    <property name="hbm2ddl.auto" value="create-drop"/>
    <!-- without below table was not created -->
    <property name="javax.persistence.schema-generation.database.action" value="drop-and-create" />
</properties>

used Wildfly's in-memory H2 database

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There is one very important detail, than can possibly stop your hibernate from generating tables (assuming You already have set the hibernate.hbm2ddl.auto). You will also need the @Table annotation!

@Entity
@Table(name = "test_entity")
    public class TestEntity {
}

It has already helped in my case at least 3 times - still cannot remember it ;)

PS. Read the hibernate docs - in most cases You will probably not want to set hibernate.hbm2ddl.auto to create-drop, because it deletes Your tables after stopping the app.

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In applicationContext.xml file:

<bean id="entityManagerFactoryBean" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
      <property name="dataSource" ref="dataSource" />
      <!-- This makes /META-INF/persistence.xml is no longer necessary -->
      <property name="packagesToScan" value="com.howtodoinjava.demo.model" />
      <!-- JpaVendorAdapter implementation for Hibernate EntityManager.
           Exposes Hibernate's persistence provider and EntityManager extension interface -->
      <property name="jpaVendorAdapter">
         <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
      </property>
      <property name="jpaProperties">
         <props>
            <prop key="hibernate.hbm2ddl.auto">update</prop>
            <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
         </props>
      </property>
   </bean>

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In support to @thorinkor's answer I would extend my answer to use not only @Table (name = "table_name") annotation for entity, but also every child variable of entity class should be annotated with @Column(name = "col_name"). This results into seamless updation to the table on the go.

For those who are looking for a Java class based hibernate config, the rule applies in java based configurations also(NewHibernateUtil). Hope it helps someone else.

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Hibernate hbm2ddl.auto:

Automatically validates or exports schema DDL to the database when the SessionFactory is created. With create-drop, the database schema will be dropped when the SessionFactory is closed explicitly. e.g. validate | update | create | create-drop

Please check the link for more details.

참고URL : https://stackoverflow.com/questions/306806/hibernate-automatically-creating-updating-the-db-tables-based-on-entity-classes