Right, this is a bit embarrassing :-D - after complaining that reference
descriptors are not inherited in multi-table inheritence, I'm now going
to have to claim that they are. Sometimes.
My person class also has a reference to an address object. When I
retrieve a Student object (that inherits from Person), I can access the
address perfectly. This is why I've been so puzzled by the problems with
the User class.
This also works with lists. Person also has a list of qualifications,
that can be accessed from the Student object.
So the question is, why does the inheritence work between Student and
Person, but not between them and User?
Can someone confirm whether I should be using the extents tags as well
as the multi-table inheritence?
Here is the Student class-descriptor
<!-- STUDENT -->
<class-descriptor class="com.mp.hato.ojb.OJBStudent" table="students">
<field-descriptor name="id" column="user_id" jdbc-type="INTEGER"
primarykey="true"/>
<field-descriptor name="notes" column="notes"
jdbc-type="VARCHAR"/>
<reference-descriptor name="super"
class-ref="com.mp.hato.ojb.OJBPerson" auto-retrieve="true"
auto-update="true" auto-delete="true">
<foreignkey field-ref="id"/>
</reference-descriptor>
</class-descriptor>
The address class-descriptor
<!-- ADDRESS -->
<class-descriptor class="com.mp.hato.ojb.OJBAddress" proxy="dynamic"
table="addresses">
<field-descriptor name="id" column="uid"
jdbc-type="INTEGER" primarykey="true" autoincrement="true"/>
<field-descriptor name="line1" column="LINE1"
jdbc-type="VARCHAR"/>
<field-descriptor name="line2" column="LINE2"
jdbc-type="VARCHAR"/>
<field-descriptor name="town" column="TOWN"
jdbc-type="VARCHAR"/>
<field-descriptor name="postcode" column="POSTCODE"
jdbc-type="VARCHAR"/>
</class-descriptor>
And the reference tag from the Person class-descriptor
<field-descriptor name="homeAddressId"
column="homeAddress" jdbc-type="INTEGER"/>
<reference-descriptor name="homeAddress"
class-ref="com.mp.hato.ojb.OJBAddress" auto-retrieve="true"
auto-update="true" auto-delete="true">
<foreignkey field-ref="homeAddressId"/>
</reference-descriptor>
The only difference that I could think of is that in the Person class,
if the address is null, the getHomeAddress method will create a blank
address - this isn't what I'm getting back though, I'm getting the
correct data from the database. However, implementing a similar check
for the getUserStatus method did not solve the problem. (I also tried
making the primary keys all autoincrement so they are the same, as Tom
suggested, but again, no joy)
Keith
>>> [EMAIL PROTECTED] 04/07/04 11:03AM >>>
Hi Tom,
Thomas Dudziak wrote:
> I wasn't aware that reference descriptors can be inherited !
The problem is that they can't ;-)
But to make the "Mapping Classes on Multiple Joined Tables" feature
full
compatible we need inheritance of references in this case or the
possibility to resolve the path to the reference.
> Is this
> somewhere in the docs ? I gotta check if this should be handled by
the
> XDoclet module ...
I will add a known issue note to release-notes, because I don't think
we
will be able to fix this before final 1.0.
regards,
Armin
>
> Keith, please ignore my post then ;-)
>
> Tom
>
> On Wed, 7 Apr 2004, Armin Waibel wrote:
>
>
>>Hi Keith,
>>
>>this is a known issue (sorry forget to answer your previous post). I
>>checked in a test called
>>InheritanceMultipleTableTest#testQuery_InheritedReference a few days
ago.
>>I don't know a workaround for this problem. If you declare the
reference
>>in the sub-class Person too you have to modify the sub-class table
and
>>this will cause side-effects if you want all User with a specific
status.
>>The problem is that the path "userStatus.name" could not be resolved
by
>>SqlGeneratorDefaultImpl.
>>
>>regards,
>>Armin
>
>
>
>
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