Cosmo 1.0 Dao Layer

The Data Access Object encapsulates access to persistent data. They are responsible for CRUD operations for persistent cosmo model objects. Because Cosmo uses Hibernate as an ORM, the DAO implementations are based on Spring's HibernateDaoSupport class, which provides access to a Hibernate Session . Cosmo uses Spring's declarative transaction framework which means the dao's require no transaction code. It is assumed that the transaction is controlled in another layer.

Item Fiilters

An ItemFilter is basically a big AND query. All the criteria set on an ItemFilter is ANDed together to match results.

Examples:

Find all NoteItem s that belong to a collection and match a displayName:

    NoteItemFilter filter = new NoteItemFilter();
    filter.setParent(parent);
    filter.setDisplayName(Restrictions.eq("matchme"));
 
    Set<Item> results = contentDao.findItems(filter);
    

Find all NoteItem s that belong to a collection, match the displayName, and have an EventStamp and occur in a specified data range:

    NoteItemFilter filter = new NoteItemFilter();
    filter.setParent(parent);
    filter.setDisplayName(Restrictions.eq("matchme"));
    EventStampFilter eventFilter = new EventStampFilter();
    Period period = new Period(new DateTime("20070101T100000Z"), new DateTime("20070201T100000Z"));
    eventFilter.setPeriod(period);
    filter.getStampFilters().add(eventFilter);

    Set<Item> results = contentDao.findItems(filter);
    

For more information on how to use filters, refer to examples in the source (org.osaf.cosmo.service.impl.StandardTriageQueryProcessor) and the unit tests.

-- RandyLetness - 25 Jun 2008