Ruby on Rails - has_many:through association in ruby on rails - ruby on rails tutorial - rails guides - rails tutorial - ruby rails
A has_many :through association is often used to set up a many-to-many connection with another model. This association indicates that the declaring model can be matched with zero or more instances of another model by proceeding through a third model.
Example
- Consider a medical practice where patients make appointments to see physicians.
- The relevant association declarations could look like this:
class Physician < ApplicationRecord
has_many :appointments
has_many :patients, through: :appointments
end
class Appointment < ApplicationRecord
belongs_to :physician
belongs_to :patient
end
class Patient < ApplicationRecord
has_many :appointments
has_many :physicians, through: :appointments
end