Question

I have a foo that has a relationship to many bar’s.

When I delete bar’s in my system I want to keep them in the database for some crazy business reason so I just set a deleted field to true.

Can I specify in my hibernate mapping that I only want my collection to hold elements where that field is false?

Answer 1

Hibernate provides filters to accomplish this.

Example beans:

public class Foo {     private Long id;     private String text;     private Set<Bar> bars = new HashSet<Bar>();         // constructors, getters, setters }  public class Bar {     private Long id;     private boolean deleted;     private String text;     // constructors, getters, setters } 

Example mappings NB: the filter element

<hibernate-mapping package='org.nkl.hib'>   <class name='Foo'>     <id name='id' column='FOO_ID'>       <generator class='sequence' />     </id>     <property name='text' />     <set name='bars' cascade='all' fetch='join'>       <key column='FOO_ID' />       <one-to-many class='Bar' />       <filter name='deleted' condition=':deleted = deleted' />     </set>   </class>   <filter-def name='deleted'>     <filter-param name='deleted' type='boolean' />   </filter-def> </hibernate-mapping>  <hibernate-mapping package='org.nkl.hib'>   <class name='Bar'>     <id name='id' column='BAR_ID'>       <generator class='sequence' />     </id>     <property name='text' />     <property name='deleted' />   </class> </hibernate-mapping> 

Example unit test:

public class FooBarTest {      private static SessionFactory sessionFactory;      @AfterClass     public static void closeSessionFactory() {         sessionFactory.close();     }      @BeforeClass     public static void setupSessionFactory() {         Configuration configuration = new Configuration();         configuration.configure();         sessionFactory = configuration.buildSessionFactory();     }      @Test     public void testBarFilter() {         doInTransaction(new Command() {             public void execute(Session session) {                 Foo foo = new Foo('foo');                 foo.addBar(new Bar('bar1'));                 foo.addBar(new Bar('bar2'));                 foo.addBar(new Bar('bar3'));                 session.save(foo);             }         });          doInTransaction(new Command() {             public void execute(Session session) {                 Bar bar = (Bar) session.createQuery(                         'from Bar b where b.text = 'bar2'').                         uniqueResult();                 bar.setDeleted(true);                 session.update(bar);             }         });          doInTransaction(new Command() {             public void execute(Session session) {                 session.enableFilter('deleted').                         setParameter('deleted', Boolean.FALSE);                 Foo foo = (Foo) session.createQuery('from Foo').                         uniqueResult();                 assertEquals(2, foo.getBars().size());             }         });     }      private void doInTransaction(Command command) {         Session session = sessionFactory.openSession();         Transaction tx = session.beginTransaction();         command.execute(session);         tx.commit();         session.close();     } }  interface Command {     public void execute(Session session); }