导轨：inverse_of和扩展协会 [英] Rails: :inverse_of and Association extensions

问题描述

我有以下建立

class Player < ActiveRecord::Base
  has_many :cards, :inverse_of => :player do
    def in_hand
      find_all_by_location('hand')
    end
  end
end

class Card < ActiveRecord::Base
  belongs_to :player, :inverse_of => :cards
end

这意味着以下工作：

p = Player.find(:first)
c = p.cards[0]
p.score # => 2
c.player.score # => 2
p.score += 1
c.player.score # => 3
c.player.score += 2
p.score # => 5

但下面不行为相同的方式：

But the following doesn't behave the same way:

p = Player.find(:first)
c = p.cards.in_hand[0]
p.score # => 2
c.player.score # => 2
p.score += 1
c.player.score # => 2
c.player.score += 2
p.score # => 3

d = p.cards.in_hand[1]
d.player.score # => 2

我怎样才能让：inverse_of 关系延伸到扩展方法？ （这只是一个bug？）

How can I make the :inverse_of relationship extend to the extension methods? (Is this just a bug?)

推荐答案

它不工作，因为in_hand的方法有一个查询可以追溯到数据库中。

It does not work because the "in_hand" method has a query that goes back to the database.

由于inverse_of选项，工作code知道如何使用已经在内存中的对象。

Because of the inverse_of option, the working code knows how to use the objects that are already in memory.

的http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html

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