Rails - Apr 2009 - Getting started with database/model relationships

Hey everyone... I''m just getting my feet wet with relational databases
using RoR models.  The software I''m putting together relies on car
parts.  Originally I had the database set up as follows

create_table :parts do |t|
  t.column :year, :string
  t.column :make, :string
  t.column :model, :string
  .
  .
  .
end

However, I now realize it''s much better to do it using relationships
instead.  Unfortunately, I''m not too familiar with this method and have
been reading up on it for a few hours.  I just want to post what I think
I''m supposed to be doing here and hopefully get a little feedback as to
whether I''m approaching this correctly before I start programming it
into my application...

class Year < ActiveRecord::Base
  has_many :makes
end

class Make < ActiveRecord::Base
  belongs_to :year
  has_many :models, :through => something_else
end

class Model < ActiveRecord::Base
  belongs_to :make
  has_many :parts, :through => something
end

class Part < ActiveRecord::Base
  belongs_to :model
end

However, I guess what is confusing me is that if I try to set it up this
way, if I enter a part for a 1999 Jeep Cherokee, how would I link the
part (say with part_id = 1337) to 1999, Jeep, and Cherokee?  Would I
need to refine my setup here and link the part directly to the year,
make, and model by adding belongs_to and has_many or would I simply add
a column for make_id, model_id, year_id to my "create_table :parts"
method? ie:

create_table :parts do |t|
  t.column :year_id
  t.column :make_id
  t.model :model_id
end

The other thing confusing me is the ":through => something" stuff. 
In
one example I see can see creating a friendship table that links two
users, but I''m not sure how I would apply it in this case or if it is
even smart to do it this way...

Any help would be appreciated.  Thanks!
-- 
Posted via http://www.ruby-forum.com/.

Hey Bernhard,

take a look first into this. There is a really good explanation, hope
you come along with this.

http://guides.rubyonrails.org/association_basics.html

Rafael

On 24 Apr., 07:47, Bradley Herman
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> Hey everyone... I''m just getting my feet wet with relational
databases
> using RoR models.  The software I''m putting together relies on car
> parts.  Originally I had the database set up as follows
>
> create_table :parts do |t|
>   t.column :year, :string
>   t.column :make, :string
>   t.column :model, :string
>   .
>   .
>   .
> end
>
> However, I now realize it''s much better to do it using
relationships
> instead.  Unfortunately, I''m not too familiar with this method and
have
> been reading up on it for a few hours.  I just want to post what I think
> I''m supposed to be doing here and hopefully get a little feedback
as to
> whether I''m approaching this correctly before I start programming
it
> into my application...
>
> class Year < ActiveRecord::Base
>   has_many :makes
> end
>
> class Make < ActiveRecord::Base
>   belongs_to :year
>   has_many :models, :through => something_else
> end
>
> class Model < ActiveRecord::Base
>   belongs_to :make
>   has_many :parts, :through => something
> end
>
> class Part < ActiveRecord::Base
>   belongs_to :model
> end
>
> However, I guess what is confusing me is that if I try to set it up this
> way, if I enter a part for a 1999 Jeep Cherokee, how would I link the
> part (say with part_id = 1337) to 1999, Jeep, and Cherokee?  Would I
> need to refine my setup here and link the part directly to the year,
> make, and model by adding belongs_to and has_many or would I simply add
> a column for make_id, model_id, year_id to my "create_table
:parts"
> method? ie:
>
> create_table :parts do |t|
>   t.column :year_id
>   t.column :make_id
>   t.model :model_id
> end
>
> The other thing confusing me is the ":through => something"
stuff.  In
> one example I see can see creating a friendship table that links two
> users, but I''m not sure how I would apply it in this case or if it
is
> even smart to do it this way...
>
> Any help would be appreciated.  Thanks!
> --
> Posted viahttp://www.ruby-forum.com/.

I think I''m making some progress here, but what I''m wondering
about now
is whether or not my full-text search using acts_as_ferret will still 
work.  Right now, in the old database setup I have, the text search will 
find everything in the parts table.  However, lets say I link part1 with 
model1 through a model_id (or part_id), will searching parts for 
"model1" yield a result?
-- 
Posted via http://www.ruby-forum.com/.

Okay... Here is what I have... Let me know if I should make any
refinements...

http://farm4.static.flickr.com/3316/3471892268_47af8b016f_o.jpg

class Year < ActiveRecord::Base
  has_many :makes
  has_many :models, :through => :make
  has_many :parts, :through => :model
end

class Make < ActiveRecord::Base
  belongs_to :year
  has_many :models
  has_many :parts, :through => :model
end

class Model < ActiveRecord::Base
  belongs_to :make
  belongs_to :year
  has_many :parts
end

class Part < ActiveRecord::Base
  belongs_to :model
  belongs_to :make
  belongs_to :year
end
-- 
Posted via http://www.ruby-forum.com/.

Ideally I''d like a part to have a year_id, make_id, and model_id. 
I''d
like a model to have a single make_id but have the option of belonging 
to several years (aka: Corvette could have years 1952 thru 2009).  The 
make would belong to several years and have several makes (ie. Chevy 
from 1911-Present, and models like Corvette, Malibu, Camaro, etc...).  I 
don''t know why this is confusing me so much, but any help would be 
appreciated.
-- 
Posted via http://www.ruby-forum.com/.