ruby-on-rails - Rails ActiveRecord:PG::错误:错误:列引用 "created_at"不明确

Question

我正在努力解决对象中的错误，但完全不确定问题出在哪里。

这是模型的样子:

class Car < ActiveRecord::Base  
  has_many :car_colors
  has_many :colors, :through => :car_colors
end

class CarColor < ActiveRecord::Base
  belongs_to :color
  belongs_to :car
end

class Color < ActiveRecord::Base  
  has_many :car_colors
  has_many :cars, :through => :car_colors
end

这里是查询:

@cars = Car.all(:joins => :car_colors, :conditions => { :car_colors => {:color_id => params[:id_number]}}, :order => "cars.created_at DESC")

错误输出:

PG::Error: ERROR:  column reference "created_at" is ambiguous
LINE 1: ...d" WHERE "car_colors"."color_id" = 2 AND (created_at...
                                                             ^
: SELECT "cars".* FROM "cars" INNER JOIN "car_colors" ON "car_colors"."car_id" = "cars"."id" WHERE "car_colors"."color_id" = 2 AND (created_at > '2013-05-03 12:28:36.551058') ORDER BY cars.created_at DESC

生成的 SQL 查询(在错误消息下方)似乎没有问题，但是是什么导致了错误消息？

提前谢谢你。

Answer 1

car_colors 表中可能有一个 created_at 字段。 created_at 可能应该是 cars.created_at 以消除歧义。