java - 如何通过jpql查询获取列表到构造函数

Question

我需要通过 JPQL 查询将列表传递给 VO(值对象)。例如:

我的配音课:

public class FamilyVO {
  private String lastName;
  private List<Name> names;

  public FamilyVO () {
  }

  public FamilyVO (List<Name> names, String lastName) {
    this.names = names;
    this.lastName = lastName;
  }
}

我使用new运算符的查询:

public class FamilyRepositoryBean {

    @Override
    public List<FamilyVO> findFamilies(Long id) {

        StringBuilder jpql = new StringBuilder("SELECT new "+ FamilyVO.class.getName());
        jpql.append("(f.names, f.lastName)");
        jpql.append(" FROM Family f ");
        jpql.append(" WHERE f.id = :pId");

        Query query = em.createQuery(jpql.toString());
        query.setParameter("pId", id);

        return query.getResultList();
    }
}    

我的实体家庭:

@Entity
public class Family  {

    @OneToMany(mappedBy = "family")
    protected List<Name> names = new ArrayList<Name>();

    private String lastName;

    public Family() {
    }

    public List<Name> getNames(){
        return names;
    }

    public String getLastName() {
       return lastName;
    }
}

我的实体名称:

@Entity
public class Name  {

   @NotNull
   @ManyToOne(fetch = FetchType.LAZY, optional = false)
   private Family family;    

   public Name() {
   }

   public Family getFamily(){
        return family;
   }

}

当我运行此查询时，出现以下错误:

RuntimeException on EJB call java.lang.IllegalArgumentException: org.hibernate.hql.ast.QuerySyntaxException: Unable to locate appropriate constructor on class

Answer 1

如果你创建一个带参数的构造函数；您应该明确地提供不带参数的构造函数；

public FamilyVO (){ }