Has_many :through

Rails
1

I want to have the following relationships set up and, for the life of
me, I can’t get the bloody things to work:

class Company < ActiveRecord::Base

has_many :clients, :class_name => ‘Company’
has_many :suppliers, :class_name => ‘Company’

end

I have two tables set up called company_clients and company_suppliers
that each contain company_id and either client_id or supplier_id.

Any ideas on how I can get this to work? I’ve come up with workarounds
for it but none of them are elegant and I’d much rather do it properly.

Any help would be much appreciated.

2

On Tue, Jul 28, 2009 at 6:25 PM, Paul
Graham[email protected] wrote:

class Company < ActiveRecord::Base

has_many :clients, :class_name => ‘Company’
has_many :suppliers, :class_name => ‘Company’

end

I have two tables set up called company_clients and company_suppliers
that each contain company_id and either client_id or supplier_id.

has_many (along with a belongs_to in the other class) if for a 1-n
relation, but you are modelling an n-m relation.

class Company < ActiveRecord::Base
has_and_belongs_to_many :clients, :class_name => “Company”,
:join_table => :company_clients
has_and_belongs_to_many :suppliers, :class_name => “Company”,
:join_table => :company_suppliers
end

I’m not entirely sure that this works, but it’s more likely to.

–
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale
WWR: http://www.workingwithrails.com/person/9021-rick-denatale
LinkedIn: http://www.linkedin.com/in/rickdenatale

3

Rick Denatale wrote:

has_many (along with a belongs_to in the other class) if for a 1-n
relation, but you are modelling an n-m relation.

class Company < ActiveRecord::Base
has_and_belongs_to_many :clients, :class_name => “Company”,
:join_table => :company_clients
has_and_belongs_to_many :suppliers, :class_name => “Company”,
:join_table => :company_suppliers
end

I’m not entirely sure that this works, but it’s more likely to.

–
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale
WWR: http://www.workingwithrails.com/person/9021-rick-denatale
LinkedIn: http://www.linkedin.com/in/rickdenatale

Rick, thank you. With one small amendment, that does the job nicely. The
only thing that was missing was “:association_foreign_key => :client_id”
tacked onto the declaration (and a corresponding one for the suppliers).