ruby-on-rails - ruby on rails，has_many，定义多态关系的类名

Question

这是我从旧数据库中移动数据的代码:

class Old < ActiveRecord::Base
  establish_connection :old_version
  self.abstract_class = true

  class Recipe < self
    set_table_name :recipes
    has_many :uploaded_files, :as => :storage
  end

  class UploadedFile < self
    set_table_name :uploaded_files
    belongs_to :storage, :polymorphic => true
  end
end

当我运行以下代码时

Old::Recipe.all.each do |recipe|
  puts recipe.uploaded_files.to_sql
end

它执行此 SQL

SELECT `uploaded_files`.* FROM `uploaded_files`  WHERE `uploaded_files`.`storage_id` = 38 AND `uploaded_files`.`storage_type` = 'Old::Recipe'

问题是我得到:

`storage_type` = 'Old::Recipe'

但是我需要:

`storage_type` = 'Recipe'

如何更改多态关系的类？

has_many 的文档不给我答案。

Answer 1

最近我遇到了类似的问题，这是一个在 rails 4.2 中对我有用的解决方案:

class Recipe < self
  set_table_name :recipes
  has_many :old_files, -> (object) { unscope(where: :storage_type).where(storage_type: 'Recipe') }, class_name: 'UploadedFile'
end

您必须添加 unscope(:where)删除条件 uploaded_files.storage_type = 'Old::Recipe'从查询。