JPA 条件 Api - 不在关系实体查询中
JPA Criteria Api - Not in relation entities query
我在构建 CriteriaQuery 时遇到问题,无法检查此关系中未映射的实体。
@Entity
@Table(name="table1")
public class Entity1 {
//Some attributes
@Column
private Integer entity2ID;
}
@Entity
@Table(name="table2")
public class Entity2 {
private Integer id;
//Some attributes
@Column
private Boolean value;
}
CriteriaBuilder 代码:
public Query buildSelectQuery(EntityManager em, Criteria c) {
CriteriaBuilder cb = em.getCriteriaBuilder();
ConcreteCriteria criteria = (ConcreteCriteria) c;
CriteriaQuery<Entity1> cq = cb.createQuery(Entity1.class);
Root<Entity1> entity1root = cq.from(Entity1.class);
List<Predicate> predicates = buildPredicatesList(cb, entity1root, criteria); //other criteria in Entity1
if (criteria.isValueIsNull() != null) {
Root<Entity2> entity2root = cq.from(Entity2.class);
predicates.add(cb.equal(entity1root.get("entity2ID"), entity2root.get("id")));
predicates.add((criteria.isValueIsNull() ? cb.isNull(entity2root.get("value")) : cb.isNotNull(entity2root.get("value"))));
}
cq.where(predicates.toArray(new Predicate[predicates.size()]));
return em.createQuery(cq);
}
条件验证失败。我如何构建 CriteriaQuery,而不以一对一的关系将 Entity2
附加到 Entity1
?
我找到了答案
该行有助于映射查询中的对象。
cq.select(entity1root);
我在构建 CriteriaQuery 时遇到问题,无法检查此关系中未映射的实体。
@Entity
@Table(name="table1")
public class Entity1 {
//Some attributes
@Column
private Integer entity2ID;
}
@Entity
@Table(name="table2")
public class Entity2 {
private Integer id;
//Some attributes
@Column
private Boolean value;
}
CriteriaBuilder 代码:
public Query buildSelectQuery(EntityManager em, Criteria c) {
CriteriaBuilder cb = em.getCriteriaBuilder();
ConcreteCriteria criteria = (ConcreteCriteria) c;
CriteriaQuery<Entity1> cq = cb.createQuery(Entity1.class);
Root<Entity1> entity1root = cq.from(Entity1.class);
List<Predicate> predicates = buildPredicatesList(cb, entity1root, criteria); //other criteria in Entity1
if (criteria.isValueIsNull() != null) {
Root<Entity2> entity2root = cq.from(Entity2.class);
predicates.add(cb.equal(entity1root.get("entity2ID"), entity2root.get("id")));
predicates.add((criteria.isValueIsNull() ? cb.isNull(entity2root.get("value")) : cb.isNotNull(entity2root.get("value"))));
}
cq.where(predicates.toArray(new Predicate[predicates.size()]));
return em.createQuery(cq);
}
条件验证失败。我如何构建 CriteriaQuery,而不以一对一的关系将 Entity2
附加到 Entity1
?
我找到了答案
该行有助于映射查询中的对象。
cq.select(entity1root);