ActiveRecord，has_many: through 和 Polyformic 关联

各位,

我想确定我没理解错。请忽略这里继承的情况(SentientBeing) ，试图将重点放在 has _ many: through 关系中的多态模型上。也就是说，考虑以下..。

class Widget < ActiveRecord::Base
has_many :widget_groupings


has_many :people, :through => :widget_groupings, :source => :person, :conditions => "widget_groupings.grouper_type = 'Person'"
has_many :aliens, :through => :widget_groupings, :source => :alien, :conditions => "video_groupings.grouper_type = 'Alien'"
end


class Person < ActiveRecord::Base
has_many :widget_groupings, :as => grouper
has_many :widgets, :through => :widget_groupings
end


class Alien < ActiveRecord::Base
has_many :widget_groupings, :as => grouper
has_many :widgets, :through => :widget_groupings
end


class WidgetGrouping < ActiveRecord::Base
belongs_to :widget
belongs_to :grouper, :polymorphic => true
end

在一个完美的世界中，我希望在给定一个 Widget 和一个 Person 的情况下，执行以下操作:

widget.people << my_person

但是，当我这样做的时候，我注意到在 widget _ groupings 中，‘ grouper’的‘ type’总是 null。但是，如果我这样做:

widget.widget_groupings << WidgetGrouping.new({:widget => self, :person => my_person})

Then all works as I would have normally expected. I don't think I've ever seen this occur with non polymorphic associations and just wanted to know if this was something specific to this use case or if I'm potentially staring at a bug.

谢谢你的帮助！