Tapestry Grid & Hibernate Criteria
Tapestry Grid & Hibernate Criteria
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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();
}
}));
}
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