Rails - Jan 2006 - What''s the best way to do complex inheritance?

I have a Merchant class that has many Products.  Product is an abstract 
class which has many subclasses (ProductA, ProductB, etc).  All Products 
have common data, like ''name'', ''status'',
''created_on'', etc... but they
also have some completely different properties.

It seems like Active Record only supports Single Table Inheritance. 
This would make my Products'' table _huge_ and mostly empty.  Is there a
way around this or am I stuck with a sloppy table?  Would I be better of 
just having seperate lists for each Product that the merchant has?

-- 
Posted via http://www.ruby-forum.com/.

Stephen,
Single Table Inheritance will work in this case if you pull out the
extraneous attributes and put them in auxillary tables.  Then you can
associate the appropriate attiribute tables to subclasses of Product as
needed.
JM2C
Matt

On 1/3/06, Stephen Gerstacker <stephen@shortround.net>
wrote:
>
> I have a Merchant class that has many Products.  Product is an abstract
> class which has many subclasses (ProductA, ProductB, etc).  All Products
> have common data, like ''name'',
''status'', ''created_on'', etc... but they
> also have some completely different properties.
>
> It seems like Active Record only supports Single Table Inheritance.
> This would make my Products'' table _huge_ and mostly empty.  Is
there a
> way around this or am I stuck with a sloppy table?  Would I be better of
> just having seperate lists for each Product that the merchant has?
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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On 1/3/06, Stephen Gerstacker <stephen@shortround.net>
wrote:
> I have a Merchant class that has many Products.  Product is an abstract
> class which has many subclasses (ProductA, ProductB, etc).  All Products
> have common data, like ''name'',
''status'', ''created_on'', etc... but they
> also have some completely different properties.
>
> It seems like Active Record only supports Single Table Inheritance.
> This would make my Products'' table _huge_ and mostly empty.  Is
there a
> way around this or am I stuck with a sloppy table?  Would I be better of
> just having seperate lists for each Product that the merchant has?
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
Product.has_many :attributes

create_table(:attributes) do |t|
  t.column :key, :string
  t.column :value, :text
end

--
Kyle Maxwell
Chief Technologist
E Factor Media // FN Interactive
kyle@efactormedia.com
1-866-263-3261

Matt Goss wrote:
> Stephen,
> Single Table Inheritance will work in this case if you pull out the
> extraneous attributes and put them in auxillary tables.  Then you can
> associate the appropriate attiribute tables to subclasses of Product as
> needed.
> JM2C
> Matt
I tried something like this.  I made a ProductAData and made it belong 
to ProductA.  I then created a view so that I could create a new 
ProductA with its ProductAData along with it.  If the ProductA fields 
are valid, but the ProductAData isn''t, the new ProductA is saved to the
database without the ProductAData.  What''s the proper way to do this?

BTW, I''m a little green with this stuff (if it wasn''t
obvious).

-- 
Posted via http://www.ruby-forum.com/.