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Problems with JPA 2, an Embeddable with Map and multiple usages in Entities [message #504383]

Fri, 18 December 2009 15:34

Clemens D

Messages: 4
Registered: December 2009

Junior Member

Hi,
I have problems to implement the following mapping with JPA 2.

@Entity
public class LString implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(name="lang")
    private String language;

    private String strValue;
...
}

implements a language-specific string. Now I want to wrap that into a MultiLanguage-String that is an Embeddable.

@Embeddable
public class MultiLanguageString implements Serializable {
    private String defaultValue;

    @OneToMany(cascade=CascadeType.ALL)
    private Map<String,LString> lValues=new HashMap<String,LString>();
...
}

MultiLanguageString implements a String which has a default string value and additional language specific values (Ideally I thought it should be implemented with just a Map based on an ElementCollection within MultiLanguageString, but I know that this is not foreseen to work in JPA 2).

Now, I want to use MultiLanguageString in different classes (with the possibility of using it in the same class more than once).

@Entity
public class TestEntity implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Embedded
    @AttributeOverride(name="defaultValue", column=@Column(name="name"))
    @AssociationOverride(name="lValues", joinTable=@JoinTable(name="testentity_names"))
    private MultiLanguageString name;

    @Embedded
    @AttributeOverride(name="defaultValue", column=@Column(name="shortName"))
    @AssociationOverride(name="lValues",joinTable=@JoinTable(name="testentity_shortnames"))
    MultiLanguageString shortName;
...
}

If I try out this szenario I get an error message with a ClassCastException from EclipseLink

java.lang.ClassCastException: org.eclipse.persistence.internal.jpa.metamodel.EmbeddableTyp eImpl cannot be cast to org.eclipse.persistence.internal.jpa.metamodel

The szenario works, when I don't work with a Map but just with a Collection in MultiLanguageString. So, doesn't support JPA 2.0 such Maps as defined in MultiLanguageString in Embeddables or am I missing something?

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