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

[James Sutherland <jamesssss@xxxxxxxxx>]

The column must be in the table, you should use "service_type_id" not
"service_type_id.id".



bea-5 wrote:
> 
> 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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