A while ago I posted an article that showed how to generate a database schema from JPA annotations. Since I didn’t get the hibernate3 maven plugin working back then I used the antrun plugin as a workaround. Thanks to the help of a reader the plugin works now, so an update is in order.
Since the last article the scenario hasn’t changed: I want to generate DDL scripts for creating a database schema from JPA annotations. The created schema can then be tweaked as necessary and used in the production environment. Like the old antrun solution, the maven plugin uses the ant task from Hibernate Tools, so the resulting schema is the same.
This is how it works. Edit your pom.xml and add the plugin configuration:
<build>
<plugins>
<!-- other plugins ... -->
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>hibernate3-maven-plugin</artifactId>
<version>2.2</version>
<executions>
<execution>
<phase>process-classes</phase>
<goals>
<goal>hbm2ddl</goal>
</goals>
</execution>
</executions>
<configuration>
<components>
<component>
<name>hbm2ddl</name>
<implementation>jpaconfiguration</implementation>
</component>
</components>
<componentProperties>
<persistenceunit>Default</persistenceunit>
<outputfilename>schema.ddl</outputfilename>
<drop>false</drop>
<create>true</create>
<export>false</export>
<format>true</format>
</componentProperties>
</configuration>
</plugin>
</plugins>
</build>
Make sure that the persistence unit’s name in pom.xml (“Default” in this example) is consistent with the name assigned in persistence.xml. Additionally, you have to set the hibernate.dialect property or Hibernate won’t be able to generate a DDL script that’s compatible with your type of database.
Schema creation is executed in the process-classes phase, so you’ll find the schema in target/hibernate3/sql/schema.ddl after running mvn package (or any later phase). An alternative is to remove the <executions> element and to run the hbm2ddl goal from the command line:
mvn hibernate3:hbm2ddl
The plugin offers a lot more than just schema creation. See the plugin documentation for more information.
Matthias Friedrich's Blog 
hi,
what do you mean by “Don’t forget to set the persistence unit to whatever you declared in persistence.xml”
To use this do I need to add mappings to all my annotated classes in hibernate.cfg.xml??
thx
In your persistence.xml you’ll find an element “persistence-unit” with an attribute “name”. The value of this attribute has to match “persistenceunit” in your maven configuration. You can set them both to “Default”, for example.
You don’t have to add mappings to hibernate.cfg.xml. The maven plugin finds them automatically.
Cheers,
Matthias
Hi,
I’m getting the following error. I don’t have a hibernate config but other than trying to generate the ddl everything works fine. Do I need this file just so that the ddl can be generated?
Thanks
Bruce
[INFO] src/main/resources/hibernate.cfg.xml not found within the project. Trying absolute path.
[INFO] No hibernate configuration file loaded.
[INFO] src/main/resources/database.properties not found within the project. Trying absolute path.
[INFO] No hibernate properties file loaded.
[INFO] ————————————————————————
[ERROR] FATAL ERROR
[INFO] ————————————————————————
[INFO] The dialect was not set. Set the property hibernate.dialect.
[INFO] ————————————————————————
The plugin doesn’t know for which flavor of database it should generate the DDL script. You have to supply the “hibernate.dialect” property somehow, either using a hibernate.cfg.xml file or via persistence.xml where you can also set properties for a persistence unit.
When using hibernate config (not jpaConfiguration), these following lines applied (position hibernate.cfg.xml at absolute pasth):-
hbm2ddl
annotationconfiguration
annotationconfiguration
hibernate.cfg.xml
/Kwan
Hi-
I am trying your approach to generate db(MySQL) schema out of JPA Annotations in Maven way. I am getting following error during project build:
‘[ERROR] Persistence unit not found: ‘someunit’.
Build errors for server; org.apache.maven.lifecycle.LifecycleExecutionException: Internal error in the plugin manager executing goal ‘org.codehaus.mojo:hibernate3-maven-plugin:2.0-alpha-2:hbm2ddl’: Mojo execution failed.’
I have my persistence unit in META-INF/persistence.xml and this is the only one XML in my whole project.
For your information, here is my POM.xml hibernate3-maven configuration snippet:
org.codehaus.mojo
hibernate3-maven-plugin
2.0-alpha-2
hbm2ddl
annotationconfiguration
true
true
true
jpaconfiguration
someunit
schema.sql
schema.sql
target/test-classes
target/test-classes
${maven.test.skip}
process-test-resources
hbm2ddl
I tried in Ant way, still no GO :-(
I verified perstence.xml and its is getting into classpath of application.
Do you have any idea about whats wrong with this?
-Chandan Benjaram
Persistence.xml need not be directly in classpath. It expects it to be in folder META-INF
Did you get this resolved ?
‘[ERROR] Persistence unit not found:
I’m have the same issue.
I have the same issue too…whats the resolution?
In your persistence.xml you must have the following line:
In the pom.xml set the persistentunit like this : jpaPU
jpaPU is the name I defined in my persistence.xml
Hi, Marf! This is my error:
————————–
[0] Inside the definition for plugin ‘hibernate3-maven-plugin’ specify the following:
…
VALUE
-OR-
on the command line, specify: ‘-Dhibernatetool=VALUE’
————————–
I think this is because I set the persistent unit parameters via Spring. Do you know if there is a solution using Spring-Jpa-Hibernate? regards
I’ve solved setting the correct value for persistentUnit.
Besides, I’ve added the following tag, inside :
${basedir}/src/main/resources/database.properties
database.properties, contains the dialect of my database engine:
hibernate.dialect=org.hibernate.dialect.MySQLDialect
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Request you to update it to the latest Hibernate version.Currently it uses an older version of hibernate-core(and other supporting) API.
Here is a Dependency configuration to work with Hibernate 3.6.1 + JPA 2.0 :
org.hibernate.javax.persistence
hibernate-jpa-2.0-api
1.0.0.Final
org.hibernate
hibernate-commons-annotations
3.2.0.Final
javax.validation
validation-api
1.0.0.GA
org.hibernate
hibernate-validator
4.1.0.Final
org.hibernate
hibernate-commons-annotations
3.2.0.Final
org.hibernate
hibernate-tools
3.2.4.GA
org.hibernate
hibernate-core
3.6.1.Final
org.jboss.slf4j
slf4j-jboss-logging
1.0.2.GA
org.jboss.logging
jboss-logging
3.0.0.Beta4
Hi!
I’m using hibernate together with Spring and I do not have hibernate.cfg.xml
I receive an error “No hibernate configuration file loaded.”
How can I solve it?
Thank you
Hi Pavel,
in your case, you probably need to put a database.properties file in src/main/resources folder, containing hibernate properties (Dialect, at least)
So, mine is :
hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect
Hope this helps,
Samuel
Hi! why always error like that, do you know why ?
[ERROR] FATAL ERROR
[INFO] ————————————————————————
[INFO] The plugin descriptor for the plugin Plugin [org.codehaus.mojo:hibernate3-maven-plugin] was not found. Please verify that the plugin JAR /home/tirtavium/.m2/repository/org/codehaus/mojo/hibernate3-maven-plugin/2.2/hibernate3-maven-plugin-2.2.jar is intact.
[INFO] ————————————————————————
[INFO] Trace
java.lang.IllegalStateException: The plugin descriptor for the plugin Plugin [org.codehaus.mojo:hibernate3-maven-plugin] was not found. Please verify that the plugin JAR /home/tirtavium/.m2/repository/org/codehaus/mojo/hibernate3-maven-plugin/2.2/hibernate3-maven-plugin-2.2.jar is intact.
at org.apache.maven.plugin.DefaultPluginManager.addPlugin(DefaultPluginManager.java:360)
at org.apache.maven.plugin.DefaultPluginManager.verifyVersionedPlugin(DefaultPluginManager.java:224)
at org.apache.maven.plugin.DefaultPluginManager.verifyPlugin(DefaultPluginManager.java:184)
at org.apache.maven.plugin.DefaultPluginManager.loadPluginDescriptor(DefaultPluginManager.java:1642)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.verifyPlugin(DefaultLifecycleExecutor.java:1540)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.getMojoDescriptor(DefaultLifecycleExecutor.java:1787)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.segmentTaskListByAggregationNeeds(DefaultLifecycleExecutor.java:462)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:175)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Thank you very much !!
Great idea, and it used to work. Then it stopped working. It either hangs forever, or says that the ‘process-classes’ phase does not exist
I found that the ‘install’ phase does work, and that makes more sense to me anyway, since it is part of ‘filling’ the target directory.
GROSSO DE LA VIDA.
Estuve buscando esto por mil lados distintos, y no lo pude encontrar, hasta que te leí…
Muchas gracias!!!
(If you don’t speak spanish: “Thanks for all that fish!”)
I have commented out the section and running the command mvn hibernate3:hbm2ddl. I am getting these comment’s repeatedly and cannot go any further beyond this point.
DEBUG org.hibernate.util.DTDEntityResolver – trying to resolve system-id [http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd]
Please help!
If you are running maven behind a proxy, try to add the proxy settings, in the $MAVEN_HOME/conf/settings.xml file.