Rails - Mar 2006 - Multiple table relationships

Hello,

I''m just starting out with some Rails development and have the
following
table structure. I understand how to do a two table has many join but I
actually need to relate a third table. Here is my structure:

components
  id
  name
  updated_at

elements
  id
  name
  updated_at

element_types
  id
  name
  updated_at

components_elements
  component_id
  element_id
  element_type_id
  updated_at

My Component model has the following:

class Component < ActiveRecord::Base
  has_and_belongs_to_many :elements
end

I haven''t actually added anything to my Element model but suspect that
it
also needs a habtm association. My bigger issue is, how to I associate
things with the element_types table?

Kyle Heon
kheon@comcast.net
www.kyleheon.com


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On 24/03/06, Kyle Heon <kheon@comcast.net> wrote:
>
>
> Hello,
>
> I''m just starting out with some Rails development and have the
following
> table structure. I understand how to do a two table has many join but I
> actually need to relate a third table. Here is my structure:
>
> components
>   id
>   name
>   updated_at
>
> elements
>   id
>   name
>   updated_at
>
> element_types
>   id
>   name
>   updated_at
>
> components_elements
>   component_id
>   element_id
>   element_type_id
>   updated_at
>
> My Component model has the following:
>
> class Component < ActiveRecord::Base
>   has_and_belongs_to_many :elements
> end
>
> I haven''t actually added anything to my Element model but suspect
that it
> also needs a habtm association. My bigger issue is, how to I associate
> things with the element_types table?
>
> Kyle Heon
> kheon@comcast.net
> www.kyleheon.com
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
>
>
Well I haven''t been doing this long, but hopefully I won''t
make any
mistakes here.

class Component < ActiveRecord::Base
  has_and_belongs_to_many :elements
end

class Element < ActiveRecord::Base
  has_and_belongs_to_many :components
  belongs_to :element_type
end

class ElementType < ActiveRecord::Base
  has_many :elements
end

Hopefully that''s answered your question.
-Nathan