DTO in Scala

I haven't done anything specifically like this in Scala, but having returned recently to Java on a project that uses the DTO "pattern", I keep thinking that traits would make my life a lot simpler. The idea in my head is to have a trait that describes the common interface between the DTO object and domain model, which provides the implementation of the accessors. The domain class would extend the trait with the domain logic, and the DTO class would extend the trait with no further implementation (unless the DTOs were used in both directions, in which case you might want to have DTO specific mutators). You could have an implicit function(s) to convert between the two.

As I said, I haven't actually done this in Scala, so I'm not sure how well it would work in practice. I'm not even sure that if I was doing my current project in Scala that there would even be an explicit notion of DTOs; my thoughts above are only centered on the direct translation of that aspect of the code.

Cheers,
Kristian.

On Thu, Apr 2, 2009 at 3:38 AM, Andrés Testi <andres.a.testi@gmail.com> wrote:

Does Data Transfer Object pattern make sense in Scala? Are there
better options? Is there a kind of BeansUtils/Dozer API for mapping
scala objects?
Thanks in advance.

- Andrés

Thanks four your response, Kristian. I like the trait approach, but
since there is not automatic convertion between traits, a convertion
method (your implicit function) must be defined to perform the
mapping. Deep mapping is an additional issue.
Regards.

- Andrés

2009/4/1 Kristian Domagala :
> I haven't done anything specifically like this in Scala, but having returned
> recently to Java on a project that uses the DTO "pattern", I keep thinking
> that traits would make my life a lot simpler. The idea in my head is to have
> a trait that describes the common interface between the DTO object and
> domain model, which provides the implementation of the accessors. The domain
> class would extend the trait with the domain logic, and the DTO class would
> extend the trait with no further implementation (unless the DTOs were used
> in both directions, in which case you might want to have DTO specific
> mutators). You could have an implicit function(s) to convert between the
> two.
>
> As I said, I haven't actually done this in Scala, so I'm not sure how well
> it would work in practice. I'm not even sure that if I was doing my current
> project in Scala that there would even be an explicit notion of DTOs; my
> thoughts above are only centered on the direct translation of that aspect of
> the code.
>
> Cheers,
> Kristian.
>
> On Thu, Apr 2, 2009 at 3:38 AM, Andrés Testi
> wrote:
>>
>> Does Data Transfer Object pattern make sense in Scala? Are there
>> better options? Is there a kind of BeansUtils/Dozer API for mapping
>> scala objects?
>> Thanks in advance.
>>
>> - Andrés
>
>

Andrés,

Yes, you're right on both accounts. I'm not doing deep mapping on my current project, so I didn't consider that. As for automatic conversion, I still have a gut feeling that there would be a minimal way around it using composition (UML) & delegation in the domain model, but I haven't had an opportunity to work through and verify it.

Cheers,
Kristian.


On Sat, Apr 4, 2009 at 4:36 AM, Andrés Testi <andres.a.testi@gmail.com> wrote:

Thanks four your response, Kristian. I like the trait approach, but
since there is not automatic convertion between traits, a convertion
method (your implicit function) must be defined to perform the
mapping. Deep mapping is an additional issue.
Regards.

- Andrés

2009/4/1 Kristian Domagala <kristian.domagala@gmail.com>:
> I haven't done anything specifically like this in Scala, but having returned
> recently to Java on a project that uses the DTO "pattern", I keep thinking
> that traits would make my life a lot simpler. The idea in my head is to have
> a trait that describes the common interface between the DTO object and
> domain model, which provides the implementation of the accessors. The domain
> class would extend the trait with the domain logic, and the DTO class would
> extend the trait with no further implementation (unless the DTOs were used
> in both directions, in which case you might want to have DTO specific
> mutators). You could have an implicit function(s) to convert between the
> two.
>
> As I said, I haven't actually done this in Scala, so I'm not sure how well
> it would work in practice. I'm not even sure that if I was doing my current
> project in Scala that there would even be an explicit notion of DTOs; my
> thoughts above are only centered on the direct translation of that aspect of
> the code.
>
> Cheers,
> Kristian.
>
> On Thu, Apr 2, 2009 at 3:38 AM, Andrés Testi <andres.a.testi@gmail.com>
> wrote:
>>
>> Does Data Transfer Object pattern make sense in Scala? Are there
>> better options? Is there a kind of BeansUtils/Dozer API for mapping
>> scala objects?
>> Thanks in advance.
>>
>> - Andrés
>
>