我有一个模型,其中每个具体类都实现了表格。因此,我有一个抽象类,该类具有跨多个表的通用属性。并且我有以下实体。
@Entity
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public abstract class BaseForm{
@Id
@GeneratedValue(strategy = GenerationType.TABLE)
protected Long id;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id=id;
}
@Column(name = "submission_date")
protected Date submissionDate;
public Date getSubmissionDate() {
return submissionDate;
}
public void setSubmissionDate(Date submissionDate) {
this.submissionDate=submissionDate;
}
}
@Entity
@Table(name = "form_a")
public class FormA extends BaseForm{
@OneToMany(cascade = CascadeType.ALL, mappedBy = "formA", fetch = FetchType.LAZY)
@Cascade(value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
@Fetch(FetchMode.SUBSELECT)
@OrderBy("id")
protected List<UserForm> userForms = new ArrayList<UserForm>();
}
@Entity
@Table(name = "form_b")
public class FormB extends BaseForm{
@OneToMany(cascade = CascadeType.ALL, mappedBy = "formB", fetch = FetchType.LAZY)
@Cascade(value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
@Fetch(FetchMode.SUBSELECT)
@OrderBy("id")
protected List<UserForm> userForms = new ArrayList<UserForm>();
}
@Entity
@Table(name = "user_form")
public class UserForm {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
protected Long id;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@ManyToOne(optional = true)
protected FormA formA;
@ManyToOne(optional = true)
protected FormB formB;
@ManyToOne(optional = true)
protected User user;
}
但是每当我尝试在多态查询上使用createAlias时,选择所有加入userForms的表单以返回每个表单的用户信息。它引发一个异常。
2016-01-04 12:21:54,158错误[org.hibernate.util.JDBCExceptionReporter]不是唯一的表/别名:'userforms1_'
DetachedCriteria baseCR = DetachedCriteria.forClass(BaseForm.class);
baseCR.createAlias("userForms", "userForms");
);
baseCR.add(Restrictions.disjunction()
.add(Restrictions.isNotNull("userForms.formA"))
.add(Restrictions.isNotNull("userForms.formB"))
);
baseCR.setResultTransformer(CriteriaSpecification.DISTINCT_ROOT_ENTITY);
baseCR.setProjection(Projections.rowCount());
List results= ht.findByCriteria(baseCR);
这是生成的休眠查询
SELECT COUNT(*) AS y0_
FROM
(SELECT id,
submissionDate,
1 AS clazz_
FROM form_a
UNION
SELECT id,
submissionDate,
2 AS clazz_
FROM form_b
) this_
INNER JOIN user_form userforms1_
ON this_.id=userforms1_.formA_id
INNER JOIN user_form userforms1_
ON this_.id=userforms1_.formB_id
WHERE (userforms1_.formA IS NOT NULL
OR userforms1_.formB IS NOT NULL)
不知道会是什么问题。以及如何解决?
最佳答案
您正在使用超类别名访问子类字段,这在概念上是错误的(尽管在某些情况下可行,但显然并非总是如此)。
您应该考虑将userForms
移至基类或将查询转换为类似的内容(JPQL,只需将其转换为等效的Criteria)即可:
select bf from BaseForm bf
where bf.id in (select fa.id from FormA fa join fa.userForms)
or bf.id in (select fb.id from FormB fb join fb.userForms)