A brief summary of Rails association options (foreign_key, primary_key)

background

I was a little addicted to changing foreign keys by associating tables with each other.

Table design

Thing you want to do

I want to associate the number of products with the product_number of features.

Commentary

code

has_one :feature, foreign_key: "number", primary_key: "product_number"
belongs_to :product, foreign_key: "product_number", primary_key: "number"

In other words, when the feature is referenced from the product side, records with the same product number and feature product_number are linked. And vice versa.

Summary

foreign_key Specify a foreign key(Specify the column of the referencing table).. The default is hogehoge_id。
primary_key Column used when referencing another table(Specify the column of the referenced table)Is specified. Id by default.