Rails - Feb 2006 - help with relationship

Let''s imagine we are modelling a company that have several shops. I  
have a Worker model and a Shop model. A worker belongs_to a shop, and  
each shop has_many workers. But, in a shop there''s a distinguished  
worker that is the supervisor

     create table shops (
         ...
         worker_id integer -- the supervisor
     );

How would you express this relationship?

On Tue, 2006-02-07 at 22:59 +0100, Xavier Noria wrote:
> Let''s imagine we are modelling a company that have several shops.
I
> have a Worker model and a Shop model. A worker belongs_to a shop, and  
> each shop has_many workers. But, in a shop there''s a distinguished
> worker that is the supervisor
> 
>      create table shops (
>          ...
>          worker_id integer -- the supervisor
>      );
> 
> How would you express this relationship?
----
seems to me you have distinct tables there...

shops
employees

if your model of shops (i.e. a single shop record) might have more than
one worker/supervisor/employee then it is another table. If there can
only be one supervisor, he might be in the shop record...otherwise, you
would have another column in your ''workers'' table that adds a
''role''
function (i.e. supervisor).

Craig

Hi Xavier,

I think you would to create other table with the worker''s types

So

class  WorkerType <  AvtiveRecord::Base
  has_many :worker
end

AND

class Worker < ActiveRecord::Base
  belongs_to :worker_type
end

PD: Sorry for my english :P

Saludos,

Jean Carlo Schechnner
IDENTIDAD VIRTUAL
www.IDVIRTUAL.com
skype: identidadvirtual


On 2/7/06, Xavier Noria <fxn@hashref.com> wrote:
>
> Let''s imagine we are modelling a company that have several shops.
I
> have a Worker model and a Shop model. A worker belongs_to a shop, and
> each shop has_many workers. But, in a shop there''s a distinguished
> worker that is the supervisor
>
>      create table shops (
>          ...
>          worker_id integer -- the supervisor
>      );
>
> How would you express this relationship?
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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On Feb 7, 2006, at 23:19, Craig White wrote:
> On Tue, 2006-02-07 at 22:59 +0100, Xavier Noria wrote:
>> Let''s imagine we are modelling a company that have several
shops. I
>> have a Worker model and a Shop model. A worker belongs_to a shop, and
>> each shop has_many workers. But, in a shop there''s a
distinguished
>> worker that is the supervisor
>>
>>      create table shops (
>>          ...
>>          worker_id integer -- the supervisor
>>      );
>>
>> How would you express this relationship?
> ----
> seems to me you have distinct tables there...
>
> shops
> employees
>
> if your model of shops (i.e. a single shop record) might have more  
> than
> one worker/supervisor/employee then it is another table. If there can
> only be one supervisor, he might be in the shop record...otherwise,  
> you
> would have another column in your ''workers'' table that
adds a ''role''
> function (i.e. supervisor).
Oh sorry, I wanted to be brief but that didn''t work :-).

Yes, I have tables:

     create table workers (
       ...
       is_supervisor boolean,
       center_id     integer
     );

     create table centers (
       ...
       worker_id integer -- the supervisor
     );

and corresponding models:

     class Worker < ActiveRecord::Base
       belongs_to :center
     end

     class Center < ActiveRecord::Base
       has_many :workers
     end

Now that lacks the supervisor relationship (let''s suppose we cannot  
assume a supervisor works in the center it supervises, otherwise we  
could just grab the center_id from workers).

By imitation I would write

     class Center < ActiveRecord::Base
       has_many :workers
       belongs_to :worker
     end

but that feels strange and I don''t control whether is actually right.

-- fxn