ruby-on-rails - Rails 3 ActiveRecord 关联集合自定义方法

Question

如果我有一个拍卖记录，其中有很多与之相关的出价，我可以立即执行以下操作:

highest_bid = auction.bids.last(:all, :order => :amount)

但是如果我想让这个更清楚(因为它在代码的多个区域中使用)，我应该在哪里定义方法:

highest_bid = auction.bids.highest_bid

这实际上是可能的还是我必须下拉才能直接从 Bid 类中查找？

highest_bid = Bid.highest_on(auction)

Answer 1

对不起，我想通了。我曾尝试将该方法添加到 ActiveRecord Bid 类，但我忘记将其设为类方法，因此它看不到该方法。

class Bid < ActiveRecord::Base
  ...
  def self.highest
    last(:order => :amount)
  end

然而，这并非 100% 会处理关联。现在只是为此编写一些测试。

编辑:

快速测试似乎表明，这似乎也能神奇地处理关联。

test "highest bid finder associates with auction" do
  auction1 = install_fixture :auction, :reserve => 10
  auction2 = install_fixture :auction, :reserve => 10

  install_fixture :bid, :auction => auction1, :amount => 20, :status => Bid::ACCEPTED
  install_fixture :bid, :auction => auction1, :amount => 30, :status => Bid::ACCEPTED
  install_fixture :bid, :auction => auction2, :amount => 50, :status => Bid::ACCEPTED

  assert_equal 30, auction1.bids.highest.amount, "Highest bid should be $30"
end

如果未正确关联，该测试将找到 50 美元的出价。巫毒教;)