HABTM 2 tables 2 different relationships - ruby-on-rails

Question

I have a Service Types table containing id and name of a couple of dozen services.
I have a Projects table that has to have a list of Proposed Services, and a list of Accepted Services.
I know that I would use HABTM on both sides with a project_service_types table in between.
I can't quite figure out what to do when I have 2 different relationships between the same table. I suspect it uses the :join_table and :associated_forign_key, but I can't get it to work in my app.
thanks.

Answer 1

I solved it using HABTM...
class ServiceType < ActiveRecord::Base
has_and_belongs_to_many :accepted_projects, :class_name => "Project", :join_table => :projects_accepted_types
has_and_belongs_to_many :proposed_projects, :class_name => "Project", :join_table => :projects_proposed_types
end
class Project < ActiveRecord::Base
has_and_belongs_to_many :accepted_types, :class_name => "ServiceType", :join_table => :projects_accepted_types
has_and_belongs_to_many :proposed_types, :class_name => "ServiceType", :join_table => :projects_proposed_types
end

Answer 2

While you can solve this with habtm, what you're talking about is the use-case for has_many :through. You want to attach a bit of information along with the relationship. To do this you create a join model that represents the relationship.
In the end this allows you to treat your service proposal as a first-class "thing" in your domain. When the service is accepted you can just change the status. This also saves a join.
Migration
create_table :project_services do |t|
t.references :project
t.references :service_type
t.string :status
end
Models
class ProjectService < ActiveRecord::Base
belongs_to :project
belongs_to :service
end
class Project < ActiveRecord::Base
has_many :project_services
has_many :accepted_services, :through => :project_services,
:conditions => { :status => 'accepted' }
has_many :proposed_services, :through => :proposed_services,
:conditions => { :status => 'proposed' }
end
class Service < ActiveRecord::Base
has_many :project_services
has_many :accepted_projects, :through => :project_services,
:conditions => { :status => 'accepted' }
has_many :proposed_projects, :through => :proposed_services,
:conditions => { :status => 'proposed' }
end

Answer 3

For that you'd probably want to use has_many :through as in:
class ProposedService < ActiveRecord::Base
belongs_to :project
belongs_to :service_type
class AcceptedService < ActiveRecord::Base
belongs_to :project
belongs_to :service_type
class Projects < ActiveRecord::Base
has_many :proposed_services
has_many :accepted_services
has_many :service_types, :through => :proposed_services
has_many :service_types, :through => :accepted_services
class ServiceTypes < ActiveRecord::Base
has_many :proposed_services
has_many :accepted_services
has_many :projects, :through => :proposed_services
has_many :projects, :through => :accepted_services
The many-to-many section here:
http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html
explains this in more detail. Hope this helps!