ruby-on-rails - Rails，按嵌套项选择

Question

class Client < ActiveRecord::Base
 attr_accessible :name
 has_many :comments, :dependent => :destroy
end

class Comment < ActiveRecord::Base
 attr_accessible :title, :date
 belongs_to :client
end

如何在评论日期“2012-01-30”之前找到所有客户？

Answer 1

假设date是一个日期类型字段

Client.joins(:comments).where(comments: { date: Date.new(2012,1,30) })