Tapestry Grid & Hibernate Criteria
Tapestry Grid & Hibernate Criteria
Join the DZone community and get the full member experience.
Join For FreeSecure your Java app or API service quickly and easily with Okta's user authentication and authorization libraries. Developer accounts are free forever. Try Okta Instead.
Tapestry Grid is a very powerful tool for displaying a list of entities. It expects a GridDataSource as source parameter. A useful tool can be a TypeCoercer which converts a Criteria to GridDataSource.
Here is a simple implementation
public class Criteria2GridDataSourceCoercion implements Coercion<Criteria, GridDataSource> {
@Override
public GridDataSource coerce(final Criteria criteria) {
return new GridDataSource() {
private List<?> cache;
private int startIndex;
@Override
public int getAvailableRows() {
setupCriteria(Projections.rowCount(), 0, 1);
long count = ((Long) criteria.uniqueResult());
return (int) count;
}
@Override
public void prepare(int startIndex, int endIndex, List<SortConstraint> sortConstraints) {
setupCriteria(null, startIndex, endIndex - startIndex + 1);
criteria.setResultTransformer(Criteria.ROOT_ENTITY);
if (sortConstraints.size() != 0) {
for (SortConstraint sortConstraint : sortConstraints) {
String propertyName = sortConstraint.getPropertyModel().getPropertyName();
criteria.addOrder(
sortConstraint.getColumnSort() == ColumnSort.ASCENDING ?
Order.asc(propertyName) : Order.desc(propertyName));
}
}
cache = criteria.list();
this.startIndex = startIndex;
}
@Override
public Object getRowValue (int index) {
return cache.get(index - startIndex);
}
@Override
public Class getRowType() {
if (cache == null) {
setupCriteria(null, 0, 1);
criteria.setResultTransformer(Criteria.ROOT_ENTITY);
cache = criteria.list();
}
if (cache.size() != 0) {
return cache.get(0).getClass();
}
return null;
}
private void setupCriteria(Projection projection, int firstResult, int maxResults) {
criteria.setProjection(projection).setFirstResult(firstResult).setMaxResults
(maxResults);
}
};
}
}
and in your Module class
@Contribute(TypeCoercer.class)
public static void addCoercion(Configuration<CoercionTuple> types) {
types.add(new CoercionTuple(Criteria.class, GridDataSource.class,
new Criteria2GridDataSourceCoercion()));
}
Usage
public class SamplePage {
@Inject
private Session session;
public Criteria getCriteria() {
Criteria criteria = session.createCriteria(MyEntity.class);
return criteria;
}
}
<html xmlns:t='http://tapestry.apache.org/schema/tapestry_5_3.xsd'> <div t:type='Grid' t:source='criteria'> </div> </html>
Dragan came up with another useful Coercer to convert Criteria to Long
public static void contributeTypeCoercer(Configuration configuration) {
configuration.add(CoercionTuple.create(Criteria.class, Long.class,
new Coercion() {
@Override
public Long coerce(Criteria input) {
input = input.setProjection(Projections.rowCount());
input = input.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
return (Long) input.uniqueResult();
}
}));
configuration.add(CoercionTuple.create(Criteria.class, List.class,
new Coercion() {
@Override
public List coerce(Criteria input) {
return input.list();
}
}));
}
Secure your Java app or API service quickly and easily with Okta's user authentication and authorization libraries. Developer accounts are free forever. Try Okta Instead.
Like This Article? Read More From DZone
Published at DZone with permission of Taha Siddiqi , DZone MVB. See the original article here.
Opinions expressed by DZone contributors are their own.
{{ parent.title || parent.header.title}}
{{ parent.tldr }}
{{ parent.linkDescription }}
{{ parent.urlSource.name }}