无法将@IdClass属性用于@ManyToOne关系 [英] Cannot use an @IdClass attribute for a @ManyToOne relationship

问题描述

我有一个Gfh_i18n实体，带有复合键(@IdClass):

I have a Gfh_i18n entity, with a composite key (@IdClass):

@Entity @IdClass(es.caib.gesma.petcom.data.entity.id.Gfh_i18n_id.class)
public class Gfh_i18n implements Serializable {

  @Id @Column(length=10, nullable = false)
  private String localeId = null;

  @Id <-- This is the attribute causing issues
  private Gfh gfh = null;
  ....
}

和id类

public class Gfh_i18n_id implements Serializable {
  private String localeId = null;
  private Gfh gfh = null;
  ...
}

在撰写本文时，此方法有效.问题是我还有一个Gfh类，该类与Gfh_i18n的关系为@OneToMany:

As this is written, this works. The issue is that I also have a Gfh class which will have a @OneToMany relationship to Gfh_i18n:

@OneToMany(mappedBy="gfh")
@MapKey(name="localeId")
private Map<String, Gfh_i18n> descriptions = null;

使用Eclipse Dali，这会给我以下错误:

Using Eclipse Dali, this gives me the following error:

 In attribute 'descriptions', the "mapped by" attribute 'gfh' has an invalid mapping type for this relationship.

如果我只是想尝试，请在Gfh_1i8n

If I just try to do, in Gfh_1i8n

@Id @ManyToOne
private Gfh gfh = null;

它解决了先前的错误，但在Gfh_i18n中给出了一个，说明了这一点

it solves the previous error but gives one in Gfh_i18n, stating that

The attribute matching the ID class attribute gfh does not have the correct type es.caib.gesma.petcom.data.entity.Gfh

这个问题与我的相似，但我不完全理解为什么我应该使用@EmbeddedId(或者是否可以将@IdClass与@ManyToOne一起使用).

This question is similar to mine, but I do not fully understand why I should be using @EmbeddedId (or if there is some way to use @IdClass with @ManyToOne).

我在Hibernate(JBoss 6.1)上使用JPA 2.0

I am using JPA 2.0 over Hibernate (JBoss 6.1)

有什么想法吗?预先感谢.

Any ideas? Thanks in advance.

推荐答案

您正在处理派生身份"(在JPA 2.0规范的2.4.1节中进行了描述).

You are dealing with a "derived identity" (described in the JPA 2.0 spec, section 2.4.1).

您需要更改ID类，以便与子"实体中的父"实体字段相对应的字段(在您的情况下为gfh)具有与父"实体的单个字段(例如String)，或者，如果父"实体使用IdClass，则IdClass(例如Gfh_id).

You need to change your ID class so the field corresponding to the "parent" entity field in the "child" entity (in your case gfh) has a type that corresponds to either the "parent" entity's single @Id field (e.g. String) or, if the "parent" entity uses an IdClass, the IdClass (e.g. Gfh_id).

在Gfh_1i8n中，您应该这样声明gfh:

In Gfh_1i8n, you should declare gfh like this:

@Id @ManyToOne
private Gfh gfh = null;

假设GFH具有单个@Id类型为String的字段，则您的ID类应如下所示:

Assuming GFH has a single @Id field of type String, your ID class should look like this:

public class Gfh_i18n_id implements Serializable {
  private String localeId = null;
  private String gfh = null;
  ...
}

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