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VisualizaçõesReferencing the same model twice in Rails with a simple entity?
I have the Shipping entity that references the Address entity twice, for example:
and the shipment model is as follows belonging twice to the entity of address (address_from, address_to):
class Shipment < ApplicationRecord
belongs_to :address_from, :class_name => 'Address'
belongs_to :address_to, :class_name => 'Address'
end
but I'm not very clear how it would look on the other side of the relationship model
class Address < ApplicationRecord
has_one :shipment
end
If it were a relationship between shipment and address it would be as follows:
rails g model Address
rails g model Shipment address:references
but I am not very clear how to relate them twice in this case
Any advice would be highly appreciated, thanks.
1 Respostas
Responde à pergunta0
You can't actually use a single assocation here as ActiveRecord does not support assocations where the foreign key could be in one of two columns. Each has_one/has_many corresponds to a single foreign key column on the inverse side.
Instead you need one assocation on Address for each foreign key on Shipment:
class Shipment < ApplicationRecord
belongs_to :address_from,
class_name: 'Address',
inverse_of: :outgoing_shipments
belongs_to :address_to,
class_name: 'Address',
inverse_of: :incoming_shipments
end
class Address < ApplicationRecord
has_many :outgoing_shipments,
class_name: 'Shipment',
foreign_key: :address_from_id,
inverse_of: :address_from
has_many :incoming_shipments,
class_name: 'Shipment',
foreign_key: :address_to_id,
inverse_of: :address_to
end
While you could use has_one here you should note that there is nothing preventing a address from having multiple shipments unless you add uniqueness constraints on shipments.address_from_id and shipments.address_to_id and validations. Not sure why you would want this though.