t.belongs_to in migration

The t.belongs_to :category is just a special helper method of rails passing in the association.

If you look in the source code belongs_to is actually an alias of references

Yes, it's an alias; It can also be written t.references category.

$ rails g migration AddUserRefToProducts user:references

this generates:

class AddUserRefToProducts < ActiveRecord::Migration
  def change
    add_reference :products, :user, index: true
  end
end

http://guides.rubyonrails.org/active_record_migrations.html#creating-a-standalone-migration

Related