Rails - Mar 2008 - has_many :through aggregation

Hello there,

I''m trying to figure out a way to use the has_many :through option to
aggregate collections in a specific way.  Here''s an example of the
issue I''m trying to address:

create_table :companies do |t|
 t.integer :parent_id
 ...
end

create_table :employees do |t|
 t.integer :company_id
end

class Employee < ActiveRecord::Base
 belongs_to :company
end

class Company < ActiveRecord::Base
 has_many :companies, :class_name => ''Company'',
:foreign_key =>
''parent_id''
 has_many :employees
 has_many :all_employees, :through => :children_companies, :source
=> :employees
end
|

A company may own other companies (has_many :companies).  Each company
has its own set of employees (has_many :employees).  What I''d like to
be able to do is have a search-able collection of all employees for a
company (including all the employees at each child company).  However,
has_many :all_employees only gives me the employees of the child
companies, but not the companies proper employees.

If I use the :finder_sql option I lose finder_in_collection on the
association which is what I''m really after.

Any advice would be immensely appreciated.

Thanks,
Patrice
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You could grab both employees collection for the current company and
all the employees collections for all of the children companies the
"has_many :all_employees" and aggregate the results (I guess removing
duplicate entries if someone worked for both companies).

On Mar 18, 2:41 pm,
"pfdemui...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org"
<pfdemui...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Hello there,
>
> I''m trying to figure out a way to use the has_many :through option
to
> aggregate collections in a specific way.  Here''s an example of the
> issue I''m trying to address:
>
> create_table :companies do |t|
>  t.integer :parent_id
>  ...
> end
>
> create_table :employees do |t|
>  t.integer :company_id
> end
>
> class Employee < ActiveRecord::Base
>  belongs_to :company
> end
>
> class Company < ActiveRecord::Base
>  has_many :companies, :class_name => ''Company'',
:foreign_key =>
> ''parent_id''
>  has_many :employees
>  has_many :all_employees, :through => :children_companies, :source
> => :employees
> end
> |
>
> A company may own other companies (has_many :companies).  Each company
> has its own set of employees (has_many :employees).  What I''d like
to
> be able to do is have a search-able collection of all employees for a
> company (including all the employees at each child company).  However,
> has_many :all_employees only gives me the employees of the child
> companies, but not the companies proper employees.
>
> If I use the :finder_sql option I lose finder_in_collection on the
> association which is what I''m really after.
>
> Any advice would be immensely appreciated.
>
> Thanks,
> Patrice
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Not sure what you mean by ''aggregate the results''?  Adding the
two
collections together with ''+'' returns an array that does not
respond
to find(:all, :conditions => ...).

-Patrice

On Mar 18, 4:04 pm, "ESPN...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org"
<ESPN3.DL-
Community...-xX8xgfAcNKEAvxtiuMwx3w@public.gmane.org>
wrote:
> You could grab both employees collection for the current company and
> all the employees collections for all of the children companies the
> "has_many :all_employees" and aggregate the results (I guess
removing
> duplicate entries if someone worked for both companies).
>
> On Mar 18, 2:41 pm,
"pfdemui...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org"
<pfdemui...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> wrote:
>
> > Hello there,
>
> > I''m trying to figure out a way to use the has_many :through
option to
> > aggregate collections in a specific way.  Here''s an example
of the
> > issue I''m trying to address:
>
> > create_table :companies do |t|
> >  t.integer :parent_id
> >  ...
> > end
>
> > create_table :employees do |t|
> >  t.integer :company_id
> > end
>
> > class Employee < ActiveRecord::Base
> >  belongs_to :company
> > end
>
> > class Company < ActiveRecord::Base
> >  has_many :companies, :class_name => ''Company'',
:foreign_key =>
> > ''parent_id''
> >  has_many :employees
> >  has_many :all_employees, :through => :children_companies, :source
> > => :employees
> > end
> > |
>
> > A company may own other companies (has_many :companies).  Each company
> > has its own set of employees (has_many :employees).  What I''d
like to
> > be able to do is have a search-able collection of all employees for a
> > company (including all the employees at each child company).  However,
> > has_many :all_employees only gives me the employees of the child
> > companies, but not the companies proper employees.
>
> > If I use the :finder_sql option I lose finder_in_collection on the
> > association which is what I''m really after.
>
> > Any advice would be immensely appreciated.
>
> > Thanks,
> > Patrice
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