如何在Rails 4中設置自定義字符串外鍵？

Question

如何設置關聯使用字符串foreign_key正確設置has_one？

class Pharmaceutic < ActiveRecord::Base 
    has_one :pharmaceutic_group, foreign_key: "code" 
end 

class PharmaceuticGroup < ActiveRecord::Base 
    belongs_to :pharmaceutic, primary_key: 'code' 
end 

>> Pharmaceutic.last.pharmaceutic_group                       
    Pharmaceutic Load (0.3ms) SELECT `pharmaceutics`.* FROM `pharmaceutics` ORDER BY `pharmaceutics`.`id` DESC LIMIT 1 
    PharmaceuticGroup Load (0.3ms) SELECT `pharmaceutic_groups`.* FROM `pharmaceutic_groups` WHERE `pharmaceutic_groups`.`code` = 2 ORDER BY `pharmaceutic_groups`.`id` ASC LIMIT 1 
=> nil 
>> Pharmaceutic 
=> Pharmaceutic(id: integer, package_type: integer, group_code: string) 
>> PharmaceuticGroup 
=> PharmaceuticGroup(id: integer, code: string, name: string) 

例如當：製藥有group_code：aaa和PharmaceuticGroup具有代碼：aaa我想獲得Pharmaceutic.last.pharmaceutic_group.name => 'AAA group name'

Answer 1

我猜你應該喜歡使用Pharmaceutic belongs_to :pharmaceutic_group和PharmaceuticGroup has_many :pharmaceutics，像這樣：

class Pharmaceutic < ActiveRecord::Base 
    belongs_to :pharmaceutic_group, foreign_key: :group_code, primary_key: :code 
end 

class PharmaceuticGroup < ActiveRecord::Base 
    has_many :pharmaceutics, foreign_key: :group_code, primary_key: :code 
end