Roo jsf lazy loading with p:datatable
Hi,
Here is my implementation of lazy loading primefaces datatable.
See primefaces example http://www.primefaces.org/showcase-l...atableLazy.jsf
Here is my implementation for Account entity class.
I created public class LazyAccountDataModel extends LazyDataModel<Account> and here is load method
It worked good and can serve to insiration for you.Code:@Override public List<Account> load(int first, int pageSize, String sortField, SortOrder sortOrder, Map<String, String> filters) { logger.debug("loading lazily accounts"); List<Account> data = new ArrayList<Account>(); EntityManager entityManager = Account.entityManager(); // Criteria CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder(); CriteriaQuery<Account> accountQuery = criteriaBuilder.createQuery(Account.class); // From Root<Account> from = accountQuery.from(Account.class); //sort if(sortField != null) { if (sortOrder == SortOrder.ASCENDING) { accountQuery.orderBy(criteriaBuilder.asc(from.get(sortField))); } else { accountQuery.orderBy(criteriaBuilder.desc(from.get(sortField))); } } // filters List<Predicate> predicates = new ArrayList<Predicate>(); for(Iterator<String> it = filters.keySet().iterator(); it.hasNext();) { String filterProperty = it.next(); // table column name = field name String filterValue = filters.get(filterProperty); Expression<String> literal = criteriaBuilder.literal((String)filterValue); predicates.add(criteriaBuilder.like(from.<String>get(filterProperty), literal)); } accountQuery.where(predicates.toArray(new Predicate[predicates.size()])); // paginate data = entityManager.createQuery(accountQuery).setFirstResult(first) .setMaxResults(getPageSize()).getResultList(); // row count CriteriaQuery<Long> countQuery = criteriaBuilder.createQuery(Long.class); countQuery.select(criteriaBuilder.count(countQuery.from(Account.class))); countQuery.where(predicates.toArray(new Predicate[predicates.size()])); int rowCount = entityManager.createQuery(countQuery).getSingleResult().intValue(); setRowCount(rowCount); return data;
Problem is that I have to create for all entities this lazy load class.
Or I can make it generic ( type T ) and by reflections getMethod obtain entityManager, find and count methods.
This methods are generated by Roo with annotation @RooJpaActiveRecord.
public class LazyEntityDataModel<T> extends LazyDataModel<T>
But it will be looks like this
@SuppressWarnings("unchecked")
@Override
public T getRowData(String rowKey) {
// Originaly it was return Account.findAccount(new Long(rowKey));
try {
Method findMethod = t.getClass().getMethod("find" + t.getClass().getName(), Long.class);
return (T) findMethod.invoke(this, new Long(rowKey));
... // catch reflections exceptions
This seems for me to be better approach, but LazyEntityDataModel<T> cannot be sure that T have methods
entityManager() , find, count ...
It's possible to LazyEntityDataModel<T extends RooJpaActiveRecord> to be sure that T have these methods and then we no need to have that mess with reflections, but all entities will have to then implement RooJpaActiveRecord.
That are yours oppinions?
Thanks valerian
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