criteria-api

问题 The following criteria query calculates the average of rating of different groups of products. CriteriaBuilder criteriaBuilder=entityManager.getCriteriaBuilder(); CriteriaQuery<Tuple>criteriaQuery=criteriaBuilder.createQuery(Tuple.class); Metamodel metamodel=entityManager.getMetamodel(); EntityType<Product>entityType=metamodel.entity(Product.class); Root<Product>root=criteriaQuery.from(entityType); SetJoin<Product, Rating> join = root.join(Product_.ratingSet, JoinType.LEFT); Expression<Number

问题 I want to do something like this: select count(*) from (select ...) (As it would be in SQL), but in JPA. Any ideas on how I would do it? 回答1: This should do the trick (If you want to use JPA criteria API): CriteriaBuilder cb = getEntityManager().getCriteriaBuilder(); CriteriaQuery<Long> query = cb.createQuery(Long.class); Root<Entity> root = query.from(Entity.class); //Selecting the count query.select(cb.count(root)); //Create your search criteria Criteria criteria = ... //Adding search

问题 I have a join reference like following for which the first join expression is constructed by the JPA API automatically. CriteriaBuilder cb = entityManager.getCriteriaBuilder(); CriteriaQuery<Tuple> c = cb.createTupleQuery(); Root<Demand> demands = c.from(Demand.class); Join<Demand, Metadata> joinMetadata = demands.join("metadatas", JoinType.LEFT); but, I would like to add an aditional condition to my joinMetadata like Metadata.type="AFFECTATION_KEY" but I don't know how. Many thanks for any

问题 I'm trying to use Criteria API in my new project: public List<Employee> findEmps(String name) { CriteriaBuilder cb = em.getCriteriaBuilder(); CriteriaQuery<Employee> c = cb.createQuery(Employee.class); Root<Employee> emp = c.from(Employee.class); c.select(emp); c.distinct(emp); List<Predicate> criteria = new ArrayList<Predicate>(); if (name != null) { ParameterExpression<String> p = cb.parameter(String.class, "name"); criteria.add(cb.equal(emp.get("name"), p)); } /* ... */ if (criteria.size()

问题 Given the query example here: http://www.hibernatespatial.org/tutorial-hs4.html Query query = em.createQuery("select e from Event e where within(e.location, :filter) = true", Event.class); query.setParameter("filter", filter); Is it possible to rewrite the query using jpa 2 criteria api?( I am unsure how i should deal with the within(e.location, :filter) part. 回答1: I recently work at the exact same problem. My solution is a own Predicate for the within-keyword. public class WithinPredicate

问题 I am a first time user of the new JPA 2.0 Criteria API and I 'm running into a problem when I need to cast a number field to String to compare it with a String parameter. Reason is that I want to search for partial numbers, so I use a 'like' on the CriteriaBuilder. Here's a code sample: CriteriaBuilder cb = getEntityManager().getCriteriaBuilder(); CriteriaQuery<ParcelDO> cq = cb.createQuery(ParcelDO.class); Root<ParcelDO> parcelDO = cq.from(ParcelDO.class); cq.select(parcelDO); String

问题 I need to make a search method that uses the JPA Criteria API with multiple parameters. Now the problem is that not every parameter is required. So some could be null, and they shouldn't be included in the query. I've tried this with the CriteriaBuilder but I couldn't see how to make it work. With the Hibernate Criteria API this is fairly easy. Just create the criteria and then add Restrictions. Criteria criteria = session.createCriteria(someClass.class); if(someClass.getName() != null) {

问题 I'm having some trouble with setting the where clause of the following query: CriteriaBuilder cb = em.getCriteriaBuilder(); CriteriaQuery<Configuration> cq = cb.createQuery(Configuration.class); Root<Configuration> conf = cq.from(Configuration.class); MapJoin<Configuration, String, Component> mapJoin = conf.join(Configuration_.components, JoinType.LEFT); cq.where(cb.and(cb.like(mapJoin.key(), "%abc%"), cb.like(mapJoin.value().get(Component_.displayName), "%def%"))); cq.select(pc); I am

问题 I need help to convert this JPQL query in Criteria Query: SELECT u.documentList FROM Unit u WHERE u.id = :id this is what i have tried: CriteriaQuery<Document> query = builder.createQuery(Document.class); Root<Unit> root = query.from(Unit.class); Join<Unit, Document> join = root.join(Unit_.documentList); query.select(join); query.where(builder.equal(root.get(AbstractEntity_.id), entity.getId())); executing this query result in a complex SQL query that returns an empty list. IMO this should

问题 I can't understand how do a join in eclipse link with criteria. This my entity: public class A implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Basic(optional = false) @Column(name = "id") private Long id; @Column(name = "value") private String value; @OneToMany(mappedBy = "aid") private Collection<B> bCollection; } public class B implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Basic(optional = false) @Column(name = "id")