I18n 和数据库 ActiveRecord 查询有什么关系？

Question

有谁知道，I18n 和数据库有什么关系？

class DecorativeCentersSalesRepresentative < ActiveRecord::Base
  belongs_to :decorative_center, class_name: ::DecorativeCenter
  belongs_to :user, class_name: ::SalesRepresentative
end

class DecorativeCenter < ActiveRecord::Base
  has_many :decorative_centers_sales_representative
  has_many :sales_representatives,
    through: :decorative_centers_sales_representative
end

class SalesRepresentative < User
  has_many :decorative_centers_sales_representative,
    foreign_key: :user_id
  has_many :decorative_centers,
    through: :decorative_centers_sales_representative,
    foreign_key: :user_id
end

一切都好，我可以做到

SalesRepresentative.last.decorative_centers
  SalesRepresentative Load (0.7ms)  SELECT  `users`.* FROM `users` WHERE `users`.`type` IN ('SalesRepresentative')  ORDER BY `users`.`id` DESC LIMIT 1
  DecorativeCenter Load (0.3ms)  SELECT `decorative_centers`.* FROM `decorative_centers` INNER JOIN `decorative_centers_sales_representative` ON `decorative_centers`.`id` = `decorative_centers_sales_representative`.`decorative_center_id` WHERE `decorative_centers_sales_representative`.`user_id` = 4
#=> [#<DecorativeCenter:0x000000088e5578]

但是当我这样做时

DecorativeCenter.last.sales_representatives
  DecorativeCenter Load (0.2ms)  SELECT  `decorative_centers`.* FROM `decorative_centers`  ORDER BY `decorative_centers`.`id` DESC LIMIT 1
#=> I18n::InvalidLocale: :en is not a valid locale
#=> from /home/andreydeineko/.rvm/gems/ruby-2.3.0@profill-base/gems/i18n-0.7.0/lib/i18n.rb:284:in `enforce_available_locales!'

为什么？？

我知道这是一个无效的语言环境，有效的是:pl：

I18n.available_locales
#=> [:pl]
I18n.default_locale
#=> :pl

但是这些东西有什么关系？为什么我可以用一种方式查询，而不能用其他方式查询？

Answer 1

经过一段时间的调试，我发现了真正的问题。

Starting from the end:

  class HasManyThroughSourceAssociationNotFoundError < ActiveRecordError #:nodoc:
    def initialize(reflection = nil)
      if reflection
        through_reflection      = reflection.through_reflection
        source_reflection_names = reflection.source_reflection_names
        source_associations     = reflection.through_reflection.klass._reflections.keys
        super("Could not find the source association(s) #{source_reflection_names.collect(&:inspect).to_sentence(:two_words_connector => ' or ', :last_word_connector => ', or ', :locale => :en)} in model #{through_reflection.klass}. Try 'has_many #{reflection.name.inspect}, :through => #{through_reflection.name.inspect}, :source => <name>'. Is it one of #{source_associations.to_sentence(:two_words_connector => ' or ', :last_word_connector => ', or ', :locale => :en)}?")
      else
        super("Could not find the source association(s).")
      end
    end
  end

在这个错误中，语言环境是硬编码的，它是:en，这就是我什至无法收到错误消息的原因。

1) 在我的应用程序中，:en 不在可用的语言环境中，所以为了得到 Rails 即将吐出的错误消息，我暂时将应用程序的语言环境设置为 :en。

2) 现在我可以得到错误：

ActiveRecord::HasManyThroughSourceAssociationNotFoundError: Could not find the source association(s) "sales_representative" or :sales_representatives in model DecorativeCentersSalesRepresentatives. Try 'has_many :sales_representatives, :through => :decorative_centers_sales_representatives, :source => <name>'. Is it one of versions, decorative_center, or user?

简单地说，我在连接表中写的 belongs_to 是错误的。

AR 期望定义关联的名称，而不是数据库中的表。

变化很大

# (STI) table users, but AR model is called SalesRepresentative 
belongs_to :user, class_name: ::SalesRepresentative

到

# changed to real AR table name passing the foreign_key
belongs_to :sales_representative, class_name: ::SalesRepresentative, foreign_key: :user_id 

让它按预期工作。