[Dbix-class] table-per-subclass - how it works?

[Ben Tilly]

The benefits of OOP are mostly in information hiding.

If you're creating a bunch of long inheritance chains, you're probably
doing OOP poorly.  Composition is preferred.  And maps *much* more
naturally onto a relational database.

On Thu, Jun 14, 2012 at 11:37 PM, Alex Erzin <eaa-home at yandex.ru> wrote:
> Hm... it really works, but where are benefits of OOP? ;)
> There is no inheritance at all, and to access parent's properties I should call parent directly, so inheritance just replaced with incapsulation, and it's no one what i try to find.
>
> Some years ago we have implemented inheritance in ORM in some commercial project in Perl, later I have swithed to java and have found Hibernate it really cool with ORM.
> But now I have returned to Perl and I think that DBIx::Class can help me with ORM, but right now i'm confused that cannot find "standard" solution for typical task.
>
>
> 15.06.2012, 10:25, "Hailin Hu" <i at h2l.name>:
>> Is it acceptable like something below
>>
>> package Target;
>> ...
>> package Host;
>> ...
>> __PACKAGE__->belong_to('target' => 'Target', 'target_id');
>> sub column_only_exists_in_target {
>>   my $self = shift;
>>   return $self->target->column_only_exists_in_target;
>> }
>>
>> well, it is not a good solution, but it could work, I think :)
>>
>> On Fri, Jun 15, 2012 at 3:04 PM, Alex Erzin <eaa-home at yandex.ru> wrote:
>>
>>>  Hello,
>>>
>>>  I need to implement table-per-class inheritance, as it simple made in Hibernate in Java (more details can be found here http://docs.jboss.org/hibernate/orm/4.1/manual/en-US/html/ch10.html#inheritance-tablepersubclass),
>>>  but cannot find right way how to do it in DBIx::Class.
>>>
>>>  For example, I have two objects: Target (with properties ID, Description) and Host (ID, Hostname, IP), Host inherited from Target, and on table-level there are two tables Host and Target, joined by ID field.
>>>
>>>  CREATE  TABLE  `mydb`.`target` (
>>>   `target_id` INT NOT NULL ,
>>>   `description` VARCHAR(45) NULL ,
>>>   PRIMARY KEY (`target_id`) )
>>>
>>>  CREATE  TABLE `mydb`.`host` (
>>>   `target_id` INT NOT NULL ,
>>>   `hostname` VARCHAR(45) NULL ,
>>>   `ip` VARCHAR(45) NULL ,
>>>   PRIMARY KEY (`target_id`) ,
>>>   CONSTRAINT `fk_host_target`
>>>     FOREIGN KEY (`target_id` )
>>>     REFERENCES `mydb`.`target` (`target_id` )
>>>  )
>>>
>>>  How to implemeng there classes Target and Host, so it possible to write
>>>
>>>  print $target->id(), $targer->description()
>>>  print $host->id(), $host->description(), $host->hostname(), $host->ip()
>>>
>>>  ?
>>>
>>>  I have no ideas how to implement inheritance, and all my experiments are failed - from Host i cannot get access to parent properties like description.
>>>  Could you help me please (with examples)?
>>>
>>>  Thanks.
>>>
>>>  --
>>>  eaa@
>>>
>>>  _______________________________________________
>>>  List: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/dbix-class
>>>  IRC: irc.perl.org#dbix-class
>>>  SVN: http://dev.catalyst.perl.org/repos/bast/DBIx-Class/
>>>  Searchable Archive: http://www.grokbase.com/group/dbix-class@lists.scsys.co.uk
>>
>> _______________________________________________
>> List: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/dbix-class
>> IRC: irc.perl.org#dbix-class
>> SVN: http://dev.catalyst.perl.org/repos/bast/DBIx-Class/
>> Searchable Archive: http://www.grokbase.com/group/dbix-class@lists.scsys.co.uk
>
> --
> eaa@
>
> _______________________________________________
> List: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/dbix-class
> IRC: irc.perl.org#dbix-class
> SVN: http://dev.catalyst.perl.org/repos/bast/DBIx-Class/
> Searchable Archive: http://www.grokbase.com/group/dbix-class@lists.scsys.co.uk