Solved!
The following solution fixed this issue for me. Add the class below to src/java
(this class cannot be written in Groovy)
package org.example;
import org.codehaus.groovy.grails.orm.hibernate.cfg.GrailsAnnotationConfiguration;
import org.hibernate.MappingException;
import org.hibernate.mapping.JoinedSubclass;
import org.hibernate.mapping.PersistentClass;
import org.hibernate.mapping.RootClass;
import java.util.Iterator;
public class TablePerSubclassConfiguration extends GrailsAnnotationConfiguration {
private static final long serialVersionUID = 1;
private boolean alreadyProcessed = false;
@Override
protected void secondPassCompile() throws MappingException {
super.secondPassCompile();
if (alreadyProcessed) {
return;
}
for (PersistentClass persistentClass : classes.values()) {
if (persistentClass instanceof RootClass) {
RootClass rootClass = (RootClass) persistentClass;
if (rootClass.hasSubclasses()) {
Iterator subclasses = rootClass.getSubclassIterator();
while (subclasses.hasNext()) {
Object subclass = subclasses.next();
// This test ensures that foreign keys will only be created for subclasses that are
// mapped using "table per subclass"
if (subclass instanceof JoinedSubclass) {
JoinedSubclass joinedSubclass = (JoinedSubclass) subclass;
joinedSubclass.createForeignKey();
}
}
}
}
}
alreadyProcessed = true;
}
}
Then in DataSource.groovy
set this as the configuration class
dataSource {
configClass = 'org.example.TablePerSubclassConfiguration'
pooled = true
driverClassName = "org.h2.Driver"
username = "sa"
password = ""
dbCreate = "update"
url = "jdbc:h2:mem:testDb;MVCC=TRUE;LOCK_TIMEOUT=10000"
}
Update
I've submitted a pull request to Grails for this issue. The fix was included in Grails 2.3.8 or 2.3.9 (can't remember which).