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我已经款设立与此类似:的Rails 3 - 斯科普斯
class Book < ActiveRecord::Base
has_many :histories, as: :object
end
class Magazine < ActiveRecord::Base
has_many :histories, as: :object
end
class Action < ActiveRecord::Base
belongs_to :object, polymorphic: true
default_scope order(:done_at)
# a history contains an action and the time that action
# occurred on the object it belongs to
end
现在,我想对所有对象发生的5个最新的操作的列表。所以,我可以这样做:
Action.limit(5)
然而,问题是,如果两个行动近日对同一本书发生后,两个动作将被检索。我只想检索最新的一个。我如何实现这一目标?