查詢嵌入元素的集合我有以下JPA(2.0.2)實體:使用的EclipseLink
僱員
@Entity
@Table(name = "T_EMPLOYEE")
public class Employee {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
@ElementCollection
@CollectionTable(name = "T_COMPETENCE")
private Set<Competence> competences;
// Getter and setters
}
和能力
@Embeddable
public class Competence {
@JoinColumn(nullable = false)
@ManyToOne
private Skill skill;
// Getter and setters
}
(技能實體當不可t是重要的,因此被省略,各種附加屬性也是如此)。
我使用E clipseLink(2.2.0)用DAO查詢我的實體。現在,我想用下面的查詢:
public List<Employee> findBySkill(Skill skill) {
TypedQuery<Employee> query = getCurrentEntityManager().createQuery(
"SELECT e FROM Employee e JOIN e.competences c WHERE c.skill = :skill",
Employee.class);
query.setParameter("skill", skill);
return query.getResultList();
}
但它不斷拋出以下異常:
Caused by: Exception [EclipseLink-8030] (Eclipse Persistence Services - 2.2.0.v20110202-r8913): org.eclipse.persistence.exceptions.JPQLException
Exception Description: Error compiling the query [SELECT e FROM Employee e JOIN e.competences c WHERE c.skill = :skill], line 1, column 54: unknown state or association field [skill] of class [com.kaio.model.Competence].
at org.eclipse.persistence.exceptions.JPQLException.unknownAttribute(JPQLException.java:457)
at org.eclipse.persistence.internal.jpa.parsing.DotNode.validate(DotNode.java:88)
at org.eclipse.persistence.internal.jpa.parsing.Node.validate(Node.java:91)
at org.eclipse.persistence.internal.jpa.parsing.BinaryOperatorNode.validate(BinaryOperatorNode.java:34)
at org.eclipse.persistence.internal.jpa.parsing.EqualsNode.validate(EqualsNode.java:41)
at org.eclipse.persistence.internal.jpa.parsing.WhereNode.validate(WhereNode.java:34)
at org.eclipse.persistence.internal.jpa.parsing.ParseTree.validate(ParseTree.java:207)
at org.eclipse.persistence.internal.jpa.parsing.ParseTree.validate(ParseTree.java:183)
at org.eclipse.persistence.internal.jpa.parsing.ParseTree.validate(ParseTree.java:173)
at org.eclipse.persistence.internal.jpa.parsing.JPQLParseTree.populateReadQueryInternal(JPQLParseTree.java:110)
at org.eclipse.persistence.internal.jpa.parsing.JPQLParseTree.populateQuery(JPQLParseTree.java:84)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:216)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:187)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:139)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:123)
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1376)
... 48 more
的信息是很清楚的:它不能找到我的階級屬性技能權限。但在我看來,這沒有任何理由。或者我對我的問題有錯誤的看法?我應該如何在可嵌入對象列表中查詢?
任何幫助表示讚賞。
不,這是行不通的。您在JPQL中的語法意味着讓我獲得技能屬性的id屬性。這將失敗,因爲它甚至找不到技能屬性。如果我直接使用id,我不得不使用原生的sql查詢,但這不是最優的。 – jokr 2012-08-02 08:03:49
但是,您的查詢不提取技能實體。該ID仍然可以訪問,因爲能力記錄(正在提取)將有一個技能ID(參考技能表) – MattR 2012-08-02 08:08:54
我已經嘗試過了,它不起作用;)您不必取得技能實體。實際上,如果我引用像字符串這樣的基本屬性,同樣的查詢也會失敗。我將它調試到eclispelink的腸子,看起來類的能力根本沒有任何屬性。 – jokr 2012-08-02 08:22:54