Criteria, Example.create () and foreign keys...

patrick_ibg · **Joined:** Sat Sep 17, 2005 10:41 am **Posts:** 49

Maybe I'm using it wrong, but it seems that Example.create () only works for simple properties (Long/String/etc) and doesn't take into account foreign key relationships.

My use case:

Address a = new Address () ;
a.setCity ("somecity") ;
a.setState (new State ("AL")) ;

... = Example.create (a) ;

The State entity is never included in the generated SQL...

I can implement a workaround that uses reflection to include foreign key relations, but I haven't seen documentation on Example.create () to otherwise indicate that my usage isn't supported...

Any ideas?

kgignatyev · **Posted:** Wed Mar 29, 2006 7:14 pm

Try this:
Example ex = Example.create (a).excludeNone();

or set your custom property selector Example.create (a).setPropertySelector( custom );

By default NOT_NULL is used and I suspect that your state field is the nullable one

patrick_ibg · **Joined:** Sat Sep 17, 2005 10:41 am **Posts:** 49

I did not want to use "excludeNone()" as I wanted null properties to be ignored. In the end, I used the introspection workaround. For anyone who's interested:

Code:

  public <T extends BaseEntity> List<T> listByExample (T example)
  {
    /*
    return listByCriteria ((Class<T>) example.getClass(),
                           Example.create (example)
                             .ignoreCase()
                             .enableLike ()) ;
     */
    Class<T> clazz = (Class<T>) example.getClass() ;
    Criteria crit = getSession().createCriteria (clazz) ;
    crit.add (Example.create (example).ignoreCase().enableLike()) ;

    PropertyDescriptor [] pds = PropertyUtils.getPropertyDescriptors (example) ;
    for (PropertyDescriptor pd : pds) {
      Class<?> propertyClass = pd.getPropertyType () ;
      
      if (BaseEntity.class.isAssignableFrom (propertyClass)) {
        String propertyName = pd.getName () ;
        
        if (log.isDebugEnabled ())
          log.debug ("Found property '" + propertyName + "' of type " + propertyClass.getName ()) ;

        BaseEntity foreignEntity = null ;
        try {
          foreignEntity = (BaseEntity) PropertyUtils.getProperty (example, propertyName) ;
        }
        catch (Exception e) {
          log.error (e) ;
        }
        
        if (foreignEntity != null) {
          Serializable foreignId = foreignEntity.getId () ;
          if (foreignId != null) {
            // create sub-criteria based on id
            crit.createCriteria (propertyName)
              .add (Restrictions.idEq (foreignId)) ;
          }
          else {
            // create sub-criteria based on matching properties
            crit.createCriteria (propertyName)
              .add (Example.create (foreignEntity).ignoreCase().enableLike()) ;
          }
        }
      }
    }
    
    return crit.list () ;                        
  }