Re: [eclipselink-users] Use an entity as a discriminator column

[bea <beaotx@xxxxxxxxx>]

Hy,

The question is that the discriminator value is the column name in other entity. So, the next sample is incorrect, but I'd like to get something like this:

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn(name = "service_type_id.id")
.....
    @JoinColumn(name = "service_type_id", referencedColumnName = "id")
    @ManyToOne
    private ServiceType serviceTypeId;


But I get the excpention:
     MySQLSyntaxErrorException: Unknow column 'TipoServicio.id' in 'field list'. 

which is quite logical. I'd like to know if there is a way to do what I want.
Anyway, I can try to avoid using the mapped attribute as the discriminator.

Thanks!

On Mon, Nov 30, 2009 at 9:31 PM, James Sutherland <jamesssss@xxxxxxxxx> wrote:

In general I would avoid using a mapped attribute as the discriminator, as
attribute value can change, but an object's class cannot.  But I don't see
any reason why it wouldn't work, did you try it, what error do you get?

The discriminator value is just the column value, so integer id, 1, 2, 3,
etc.
You may need to make the JoinColumn as insertable/updateable=false.

bea-5 wrote:
>
> Hi,
>
> I have some entities with an joined inheritance type. In my root entity I
> have an attribute that is a @ManyToOne relationship to other table. In
> short, my entity looks like this:
>
> @Entity
> @Inheritance(strategy = InheritanceType.JOINED)
> @Table(name = "service")
> public class Service implements Serializable {
>
>     @JoinColumn(name = "service_type_id", referencedColumnName = "id")
>     @ManyToOne
>     private ServiceType serviceTypeId;
>    ....
>
> The attribute serviceTypeId is a foreign key to other entity:
>
> @Entity
> @Table(name = "service_type")
> public class TipoServicio implements Serializable {
>
>     @Id
>     @GeneratedValue(strategy = GenerationType.IDENTITY)
>     @Basic(optional = false)
>     @Column(name = "id")
>     private Integer id;
>
>     @Column(name = "name")
>     private String name;
>     ......
>
> I'd like to have as DiscriminatorColumn the field serviceTypeId, but I
> don't
> know how to do it, as that field hasn't a correct discriminatorType. Is
> there any way to do what I want?
>
> Thanks!
>
> --
> Beatriz Nombela Escobar
> beaotx@xxxxxxxxx
>
>

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Beatriz Nombela Escobar
beaotx@xxxxxxxxx