Tom,
it seems you are right with your interpretation of the JPA specification.
As a result, that means that it is impossible to use JPA to access
databases that have a foreign key constraint inside of the primary key.
Or did I oversee a possible solution other than replacing the entity
reference by a set of simple generic types?
Thanks
Markus
> My understanding is that putting @Id on a relationship field is not
> supported by version 1.0 of the JPA specification. If you look at
> section 2.1.4 of the specification it is quite specific about only
> allowing primary keys to be composed of primitive types:
>
> "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. In general, however, approximate numeric types (e.g.,
> floating point types) should
> never be used in primary keys. Entities whose primary keys use types
> other than these will not be portable.
> If generated primary keys are used, only integral types will be
> portable. If java.util.Date is
> used as a primary key field or property, the temporal type should be
> specified as DATE."
>
> I have heard some rumors that this is under discussion for the next
> version of the specification, but to be honest I am not sure. I
> suggest sending a request to the expert group. I am not sure what the
> exact email address is, but perhaps someone on this forum will be nice
> enough to post it.
>
> -Tom
>
> Markus KARG wrote:
>> I think I found a bug in TopLink and want to discuss with you before
>> hastily reporting it officially.
>>
>> There is one entity that has a compound key made up of two fields,
>> and it has a sub-entity using @Inheritance(strategy = JOINED). I can
>> insert new rows using the super class directly, but when I want to
>> use the sub-class, TopLink produces a SQL INSERT statement that just
>> fills one of the compound key's fields -- and forgets the other one!
>> Certainly the database server complains about that.
>>
>> In fact, I'd like to know whether that is a real bug or whether I am
>> doing something wrong (in that case, please tell me what I am doing
>> wrong and where in the JPA specification that is told).
>>
>> Here is the interesting part of the source code:
>>
>> @Entity
>> @Inheritance(strategy = JOINED)
>> public abstract class TheSuperClass {
>>
>> @Id
>> @ManyToOne
>> private Invoice invoice; // TheSuperClass actually is part of an
>> Invoice
>>
>> @Id
>> private int position; // Inside of the Invoice, we identify
>> multiple instances using this int
>>
>> ...
>>
>> @Entity
>> public final class TheSubClass extends TheSuperClass { // TheSubClass
>> is a specialization of TheSuperClass
>>
>> (there is no additional code in this class, since it I stripped away
>> everything for this small sample)
>>
>>
>> I am totally stuck with that problem. Please help me. :-)
>>
>> Thanks
>> Markus
>>
>
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