我不知道如何准备JPA（EclipseLink）查询（使用CtriteriaBuilder），该查询将包括来自Primefaces dataTable（延迟加载）的所有过滤器值。
找到了一个论坛条目https://forum.primefaces.org/viewtopic.php?p=83497&sid=1459f3a15c3c068aa77912f1bf495370#p83497，但我真的不明白如何将其应用于我的案例。
xhtml：
<p:dataTable id="datalist"
value="#{zadaniaController.lazyModel}"
var="item"
lazy="true"
....
控制器实现延迟加载所需的load（）方法：
@PostConstruct
public void postConstruct() {
lazyModel = new LazyDataModel<Zadanie>() {
private static final long serialVersionUID = 1L;
@Override
public List<Zadanie> load(int first, int pageSize, String sortField, SortOrder sortOrder, Map<String, Object> filters) {
if (null == sortField) {
//I want by default items to be sorted from newest to oldest
sortField = "terminWykonania";
sortOrder = SortOrder.DESCENDING;
}
List<Zadanie> result = ejbFacade.getResultList(first, pageSize, sortField, sortOrder, filters);
lazyModel.setRowCount(ejbFacade.count(filters));
return result;
}
};
}
和DAO：
@Stateless
public class ZadaniaFacade extends AbstractFacade<Zadanie> {
...
public List<Zadanie> getResultList(int first, int pageSize, String sortField, SortOrder sortOrder, Map<String, Object> filters) {
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Zadanie> cq = cb.createQuery(Zadanie.class);
Root<Zadanie> zadanie = cq.from(Zadanie.class);
if (null != filters) {
cq.where(zadaniaFacade.getFilterCondition(cb, zadanie, filters));
if (sortField != null) {
if (sortOrder == SortOrder.ASCENDING) {
cq.orderBy(cb.asc(zadanie.get(sortField)));
} else if (sortOrder == SortOrder.DESCENDING) {
cq.orderBy(cb.desc(zadanie.get(sortField)));
}
}
}
TypedQuery<Zadanie> query = em.createQuery(cq);
query.setFirstResult(first);
query.setMaxResults(pageSize);
List<Zadanie> list = query.getResultList();
return list;
}
private Predicate getFilterCondition(CriteriaBuilder cb, Root<Zadanie> zadanie, Map<String, Object> filters) {
Predicate filterCondition = cb.conjunction();
for (Map.Entry<String, Object> filter : filters.entrySet()) {
switch (filter.getKey()) {
case "status":
// I have multiple columns on the view, some are plain text that I should do LIKE, some are multiple select dropdowns, some are dates (from-to)
break;
default:
throw new AssertionError();
}
}
return filterCondition;
}
我应该如何在DAO中准备查询？
PF 6.1
答案 0 :(得分：0)
我正在研究类似的东西：
我认为您需要在DAO中使用两种方法，如下所示：
public List<Account> loadAccountsForPrject(Project project, int first, int pageSize, Map<String, SortMeta> sortBy, Map<String, FilterMeta> filterBy) {
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Account> cq = cb.createQuery(Account.class);
Root<Account> root = cq.from(Account.class);
cq.where(filterMetaToPredicate(cb, root, project, filterBy));
cq.orderBy(sortMetaToSortOrders(sortBy, cb, root));
TypedQuery<Account> q = em.createQuery(cq);
return q.setMaxResults(pageSize).setFirstResult(first).getResultList();
}
public Long countAccountsForPrject(Project project, int first, int pageSize, Map<String, SortMeta> sortBy, Map<String, FilterMeta> filterBy) {
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Long> cq = cb.createQuery(Long.class);
Root<Account> root = cq.from(Account.class);
cq.where(filterMetaToPredicate(cb, root, project, filterBy));
cq.orderBy(sortMetaToSortOrders(sortBy, cb, root));
cq.select(cb.count(root));
TypedQuery<Long> q = em.createQuery(cq);
return q.getSingleResult();
}
然后，您需要为filterMetaToPredicate(..)和sortMetaToSortOrders(..)提供实现，如果您在jsf页面中为filterBy和sortBy属性使用标准命名，那么这将更加容易匹配所需的路径表达式，然后可以使用以下通用方法：
private <T, X> Path<T> stringToPath(Root<X> r, String str) {
String[] split = str.split("\\.");
Path p = r;
for (String s : split) {
p = p.get(s);
}
return p;
}
最后，这是一个适合我的需求的filterMetaToPredicate(..)和sortMetaToSortOrders(..)的实现示例：
private Predicate filterMetaToPredicate(CriteriaBuilder cb, Root<Account> root, Project project, Map<String, FilterMeta> filterBy) throws AssertionError {
Predicate filter = cb.equal(root.get("project"), project);
for (FilterMeta fm : filterBy.values()) {
switch (fm.getFilterMatchMode()) {
case STARTS_WITH:
filter = cb.and(filter, cb.like(stringToPath(root, fm.getFilterField()), fm.getFilterValue().toString() + "%"));
break;
case ENDS_WITH:
filter = cb.and(filter, cb.like(stringToPath(root, fm.getFilterField()), "%" + fm.getFilterValue().toString()));
break;
case CONTAINS:
filter = cb.and(filter, cb.like(stringToPath(root, fm.getFilterField()), "%" + fm.getFilterValue().toString() + "%"));
break;
case EXACT:
break;
case LESS_THAN:
break;
case LESS_THAN_EQUALS:
break;
case GREATER_THAN:
break;
case GREATER_THAN_EQUALS:
break;
case EQUALS:
filter = cb.and(filter, cb.equal(stringToPath(root, fm.getFilterField()), fm.getFilterValue()));
break;
case IN:
break;
case GLOBAL:
break;
default:
throw new AssertionError(fm.getFilterMatchMode().name());
}
}
return filter;
}
private List<Order> sortMetaToSortOrders(Map<String, SortMeta> sortBy, CriteriaBuilder cb, Root<Account> root) throws AssertionError {
List<Order> sortOrders = new ArrayList<>();
for (SortMeta sm : sortBy.values()) {
switch (sm.getSortOrder()) {
case ASCENDING:
sortOrders.add(cb.asc(stringToPath(root, sm.getSortField())));
break;
case DESCENDING:
sortOrders.add(cb.desc(stringToPath(root, sm.getSortField())));
break;
case UNSORTED:
break;
default:
throw new AssertionError(sm.getSortOrder().name());
}
break;
}
return sortOrders;
}