Hi,
I’m trying to figure out the correct “Rails” way to perform validation
prior to creating a new assocation between my models. Here’s the models:
class User < ActiveRecord::Base
has_and_belongs_to_many :roles
has_many :instructorships
has_many :instructed_courses, :through => :instructorships, :source =>
:course
class Course < ActiveRecord::Base
has_many :instructorships
has_many :instructors, :through => :instructorships, :source =>
:instructor
class Instructorship < ActiveRecord::Base
belongs_to :instructor, :class_name => ‘User’, :foreign_key =>
‘user_id’
belongs_to :course
I’m trying to introduce a validation whereby only user objects with a
role
of ‘instructor’ can be assigned as an instructor on a course.
Firstly, where would this validation go? On the association model? And
secondly, what is the right way to set this up?
thanks for your help,
Cathal.
