使用整数ID类型字段的多态关联

association_class

:extend

INT_OBJECT_TYPE_TO_CLASSNAME = { 0 => \"Project\", 1 => \"Task\", 2 => \"Timesheet\" }

class CommentObjectType < ActiveRecord::Base
  module ClassNamesAsInt
    def association_class
      return INT_OBJECT_TYPE_TO_CLASSNAME[restricted_object_type].constantize
    end
  end
end

belongs_to :commentable, :polymorphic => true, :extend => CommentObjectType::ClassNamesAsInt

belongs_to :actor,              polymorphic: true

belongs_to :actor,              polymorphic: true, integer_type: true

has_many :bars, :conditions => \"whatever you want\"

set_inheritance_column :bar_type_id

belongs_to :bar, :class_name => proc{ BarType.find(self.bar_type_id).name }, :foreign_key => :bar_id