From: Markus Fuchs <Markus.Fuchs_at_Sun.COM>
Date: Tue, 07 Aug 2007 21:36:16 -0700

Hi Jeffrey,

Jeffrey Blattman wrote:

hi again markus,

Markus Fuchs wrote:

Hi Jeffrey,

Jeffrey Blattman wrote:

thanks markus,

this gets me further. the complexity is this, i essentially have three entities

1. Page
2. Portlet
3. Preferenence

simple right? a page contains a portlet contains preferences. a delete / update / etc of Page should affect all its portlets, and a delete / update / etc of a portlet should affect its preferences. each of these has a name.

to model the containment, Portlet's ID is the page name + it's own name (PortletId). that one is simple. however, when we go a level deeper to Preference, Preference's ID is the Portlet's ID + it's own name (PreferenceId).

how do i model that? PortletId is *not* a simple type, so I can't use it as an @Id field in Preference. how do i define Preference's ID fields?

Id fields:

In page: pageId
In Portlet: pageId & portletId, IdClass has pageId & portletId fields
In preference: pageId & portletId & preferenceId, IdClass has pageId & portletId & preferenceId fields

so the general ID is that each "contained" entity needs to have simple typed ID fields for every containing entity class.

Yes.

this is sort of confusing, because it means that a Preference needs to know about pages, when ideally all it would care about is the containing entity above it. but i think i get it. for example, as long as a Portlet has a unique ID, why does a Preference needs to know or care about the Page? the Portlet has already encapsulated the Page ID into it's ID, why does it need to be exposed to the  Preference?

If Preference has a relationship to Portlet, and Portlet has the composite primary key (pageId, portletId), then Preference must use a composite foreign key to specify the relationship.

when i just make it a @JoinColumn instead,

    @ManyToOne(optional = false, cascade = CascadeType.ALL)
    @Column(insertable=false, updatable=false, nullable=false, name="PORTLET_ID")
    @XmlTransient
    private Portlet portlet;

i get this ...

Exception Description: The @JoinColumns on the annotated element [private com.sun.portal.pom.Entity com.sun.portal.pom.Preference.entity] from the entity class [class com.sun.portal.pom.Preference] is incomplete. When the source entity class uses a composite primary key, a @JoinColumn must be specified for each join column using the @JoinColumns. Both the name and the referenceColumnName elements must be specified in each such @JoinColumn.

Looks like you used @JoinColumn*s*. Please check.

no, i didn't. the message is telling me that i need to specify >1 @JoinColumn's, and use a @JoinColumns to contain them. i think.

You are completely right. I was confused. Could you please send us your entity classes. This would help very much in resolving your issue.

Thanks much,

-- markus.

i eventually got something that appears to work, on TopLink. i had to remove the @JoinColumn from the @ManyToOne in Preference and Portlet. this is course means i'm missing insertable and updatable = false settings.

what am i supposed to use for the join columns? since PortletId encapsulates both the Page name and Portlet name, why does it want to to specify more than that?

i feel like i must be making this more complicated than it needs to be. all i want is to model some objects containing other objects where all operations cascade.

This should be doable. First start with the Page and Portlet classes. When this works, add Preferences and model the relationships and IdClass accordingly.

i know the 2-level case works. the 3 level case is giving me trouble because i have a composite ID that has (at least conceptually) another composite ID as a field.

-- markus.

?

Markus Fuchs wrote:

Hi Jeffrey,

Entities should not use relationship fields as part of the primary key. The JPA spec says (please see 2.1.4.):

The primary key (or field or property of a composite primary key) should be one of the following types:
any Java primitive type; any primitive wrapper type; java.lang.String; java.util.Date;
java.sql.Date.

Try changing:

public abstract class Entity implements Serializable {
    @Id
    @Column (nullable = false, name="ENTITY_NAME")
    @XmlAttribute
    private String name;

    @Id
    @Column (nullable = false, name="PAGE_ID")    
    private String pageId;


    @Column (nullable = false, name="PAGE_ID")    
    @ManyToOne (cascade = CascadeType.ALL, insertable=false, updatable=false)
    private Page page = null;
...
}

public class EntityId implements Serializable {
    private String name;
    private String pageId;
...
}
   
  

-- markus.

Entity
Jeffrey Blattman wrote:

hi,

2.0-b56, i'm seeing this ...

Exception Description: Invalid composite primary key specification. The names of the primary key fields or properties in the primary key class [com.sun.portal.pom.EntityId] and those of the entity bean class [class com.sun.portal.pom.Entity] must correspond and their types must be the same. Also, ensure that you have specified id elements for the corresponding attributes in XML and/or an @Id on the corresponding fields or properties of the entity class.

i've attached the two classes. Entity has IDs name and page, and EntityId has fields name and page. same name, same type. i can zip the maven2 project so the problem can be reproduced, if that helps.

what am i missing?

thanks.