ruby-on-rails - 通过多态关联查询

Question

只是在 RoR 周围玩耍，试图通过一些建模找到方法。请注意以下代码：

 class Picture < ActiveRecord::Base
      belongs_to :imageable, :polymorphic => true
 end

 class Employee < ActiveRecord::Base
      has_many :pictures, :as => :imageable
 end

 class Product < ActiveRecord::Base
      has_many :pictures, :as => :imageable
 end

有没有办法通过特定图片获取产品？ 我正在尝试这个，但它不起作用：

picure = Picture.last
product = Product.where(picture: picure)

它失败了：

SQLite3::SQLException: no such column: products.picture: SELECT "products".*
FROM "products" WHERE "products"."picture" IS NULL LIMIT 1```

Answer 1

如果您有 的实例Picture @picture，则可以使用belongs_to来获取它的关联Product（假设它Picture实际上属于Productand的实例Employee）

product = @picture.imageable