在 JPA CriteriaQuery 中使用 @Embeddable 实体

Question

假设我有以下示例实体 - 一个是@Embeddable嵌入在另一个中的@Entity：

@Embeddable
public class ContactInfoEntity {

    @Column
    private String phone;

    @Column
    private String zipCode;
}

@Entity
@Table(name = "EMPLOYEE")
public class EmployeeEntity {

    @Id
    @Column(name = "EMPLOYEE_ID")
    private Long employeeId;

    @Embedded
    @AttributeOverrides({
        @AttributeOverride(name = "phone",
                           column = @Column(name = "EMPLOYEE_PHONE")),
        @AttributeOverride(name = "zipCode",
                           column = @Column(name = "EMPLOYEE_ZIP_CODE"))
    })
    private ContactInfoEntity employeeContactInfo;
}

openjpa-maven-plugin 生成的元模型类只包含一个employeeContactInfo变量，而不包含@AttributeOverride列。

现在假设我想这样做：

选择EMPLOYEE_ID和EMPLOYEE_PHONE其中EMPLOYEE_ZIP_CODE等于“123456”

我如何将其创建为CriteriaQuery?

CriteriaBuilder cb = entityManager.getCriteriaBuilder();

CriteriaQuery<String> qDef = cb.createQuery(String.class);
Root<EmployeeEntity> e = qDef.from(EmployeeEntity.class);
qDef.select(e.get(EmployeeEntity_.employeeId),
            e.get(????))
    .where(cb.equal(e.get(????), "123456"));

return entityManager.createQuery(qDef).getResultList();

Answer 1

示例方法可能如下所示：

CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Object[]> qDef = cb.createQuery(Object[].class);
Root<EmployeeEntity> e = qDef.from(EmployeeEntity.class);
qDef.multiselect(
     e.get(EmployeeEntity_.employeeId),
     e.get(EmployeeEntity_.employeeContactInfo).get(ContactInfoEntity_.phone));
qDef.where(
     cb.equal(
        e.get(EmployeeEntity_.employeeContactInfo).get(ContactInfoEntity_.zipCode), 
        cb.literal("123456")));

List<Object[]> objects = em.createQuery(qDef).getResultList();
for (Object[] element : objects) {
    System.out.format("%d %s", element[0], element[1]);
}

根据您的偏好，您可能还希望获得查询结果：

• 构造函数表达式

  public class EmployeeEntityResult {
      private int id;
      private String phone;
  
      public EmployeeEntityResult(int id, String phone) {
          this.id = id;
          this.phone = phone;
      }
      ...
  }
  

  CriteriaQuery<EmployeeEntityResult> cq = cb.createQuery(EmployeeEntityResult.class);
  ...
  List<EmployeeEntityResult> result = em.createQuery(cq).getResultList();
  for (EmployeeEntityResult element : result) {
      System.out.format("%d %s", element.getId(), element.getPhone());
  }
  

• 元组

  CriteriaQuery<Tuple> cq = cb.createTupleQuery();
  ...
  cq.select(
     cb.tuple(
        e.get(EmployeeEntity_.employeeId)
         .alias("id"),
        e.get(EmployeeEntity_.employeeContactInfo).get(ContactInfoEntity_.phone)
         .alias("phone")));
  ...
  List<Tuple> tuple = em.createQuery(cq).getResultList();
  for (Tuple element : tuple) {
      System.out.format("%d %s", element.get("id"), element.get("phone"));
  }
  

JPQL 查询如下所示：

SELECT e.id, e.employeeContactInfo.phone
FROM EmployeeEntity e
WHERE e.employeeContactInfo.zipCode = '123456'