Has_one通过AND has_many通过在一起

Question

Hello i have 3 models:

• Sale
• Customer
• Customer Address

-Each SALE should have only one CUSTOMER

-Each CUSTOMER can have more than one SALE

That works great, there's no problem here, but now i need something like this:

-Each SALE should have only one CUSTOMER_ADDRESS

-Each CUSTOMER can have more than one CUSTOMER_ADDRESS

---

And then, how can i do this?

Can i use has_one through and has_many through together?

Answer 1

Start by creating a 1-n association between Customer and Address:

class Customer < ApplicationRecord
  has_many :addresses
end

class Address < ApplicationRecord
  belongs_to :customer
end

Then add the order model and setup the associations:

class Customer < ApplicationRecord
  has_many :addresses
  has_many :sales
end

class Address < ApplicationRecord
  belongs_to :customer
  has_many :sales_as_shipping_address, class_name: 'Sale',
                                       foreign_key: 'shipping_address_id'
end

class Sale < ApplicationRecord
  belongs_to :customer
  belongs_to :shipping_address, class_name: 'Address'
end

This creates two seperate associations - both Sale and Customer have distinct associations to Address.

If you want to join Customer to Address via sale we can do:

class Customer < ApplicationRecord
  has_many :addresses
  has_many :sales
  has_many :shipping_addresses, through: :sales, 
                               source: :shipping_address
end