Rails - Jul 2010 - Can you have a model with attributes of another model?

Ok so basically I have a problem. Im relatively new to rails and i seem
to have come to a dead end. I wanted a model that could either be a URL,
a video, a picture or a sound recording. Obviously this is impossible. I
am gonna use attachment_fu if that helps. So whats the most DRY way of
doing this. Each media thing, whether it be a video, a picture, a URL or
a sound file must be classified under the same thing as, lets say a
media object. Consequently they share attributes, like an id, a upload
date, a description etc. However they differ in their actual media
format.

Does anyone know how I should make my models and controllers.
Thanks!
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Zack,


Tuesday, July 13, 2010, 3:25:03 PM, you wrote:

ZN> Ok so basically I have a problem. Im relatively new to rails and i seem
ZN> to have come to a dead end. I wanted a model that could either be a URL,
ZN> a video, a picture or a sound recording. Obviously this is impossible. I
ZN> am gonna use attachment_fu if that helps. So whats the most DRY way of
ZN> doing this. Each media thing, whether it be a video, a picture, a URL or
ZN> a sound file must be classified under the same thing as, lets say a
ZN> media object. Consequently they share attributes, like an id, a upload
ZN> date, a description etc. However they differ in their actual media
ZN> format.

ZN> Does anyone know how I should make my models and controllers.
ZN> Thanks!
ZN> -- 
ZN> Posted via http://www.ruby-forum.com/.

Two possibilities come to mind: Subclassing and Mixins.

You can create


-----------

class MediabBase < ActiveRecord::Base
  #attributes
end

class VideoMedia < MediaBase
  #more attributes
end

class JpegMedia < MediaBase
  #other attributes
end

-----------


Ill let someone else explain how to do Mixins.



Caution: I''ve been doing Rails for about 6 months but still consider
myself a novice.  My answer may be grossly wrong.

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On Tue, Jul 13, 2010 at 4:25 PM, Zack Nathan
<lists-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org>
wrote:
> Ok so basically I have a problem. Im relatively new to rails and i seem
> to have come to a dead end. I wanted a model that could either be a URL,
> a video, a picture or a sound recording. Obviously this is impossible. I
> am gonna use attachment_fu if that helps. So whats the most DRY way of
> doing this. Each media thing, whether it be a video, a picture, a URL or
> a sound file must be classified under the same thing as, lets say a
> media object. Consequently they share attributes, like an id, a upload
> date, a description etc. However they differ in their actual media
> format.
>
> Does anyone know how I should make my models and controllers.
> Thanks!
You probably want to use polymorphic associations.

http://guides.rubyonrails.org/association_basics.html#polymorphic-associations


-- 
Greg Donald
destiney.com | gregdonald.com

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Greg Donald wrote:
> On Tue, Jul 13, 2010 at 4:25 PM, Zack Nathan
<lists-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org>
> wrote:
>> Does anyone know how I should make my models and controllers.
>> Thanks!
> 
> You probably want to use polymorphic associations.
> 
>
http://guides.rubyonrails.org/association_basics.html#polymorphic-associations
> 
> 
> --
> Greg Donald
> destiney.com | gregdonald.com
hey thanks for the reply. Your right, I thought about it more and 
polymorphism is exactly what I need. However, I want a media object to 
be either a picture, a video, a sound file or a link. So that means 
links, pictures, videos and sound files have the attributes of a media 
object but are their own media. If that makes any sense?
So for example id like to be able to do: 
MediaObject.find_by_video(example_media_object.content) or something 
like that. I dont really know how to explain this in rails, but I can do 
this easily in java haha.

Thanks.
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Ok thanks!
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