Hibernate Tips is a series of posts in which I describe a quick and easy solution for common Hibernate questions. If you have a question you like me to answer, please leave a comment below.
I want to use a database setup script instead of Hibernate’s schema generation. What’s the easiest way to create this script for an existing entity model?
JPA 2.1 introduced a schema generation features which can setup your database or export the generated commands to a file. You just have to set the following configuration parameters in your persistence.xml file to activate it:
Defines which scripts the persistence provider shall create. You can choose between none, create, drop-and-create, drop.
A script target needs to be defined for each script to be created.
Defines the target location of the create script generated by the persistence provider as a file URL or a java.IO.Writer.
Defines the target location of the drop script generated by the persistence provider as a file URL or a java.IO.Writer.
Here you can see a persistence.xml configuration that generates a create and a drop script based on the entity mapping information
<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.1" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"> <persistence-unit name="EFS2015-persistence-unit" transaction-type="JTA"> <description>Forge Persistence Unit</description> <provider>org.hibernate.ejb.HibernatePersistence</provider> <jta-data-source>java:jboss/datasources/ExampleDS</jta-data-source> <exclude-unlisted-classes>false</exclude-unlisted-classes> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/> <property name="javax.persistence.schema-generation.scripts.action" value="drop-and-create"/> <property name="javax.persistence.schema-generation.scripts.create-target" value="./create.sql"/> <property name="javax.persistence.schema-generation.scripts.drop-target" value="./drop.sql"/> </properties> </persistence-unit> </persistence>
You can use JPA’s schema generation feature also to setup and initialize databases based on the entity mapping information or a set of SQL scripts. I explain it in more detail in my post Standardized schema generation and data loading with JPA 2.1.
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