Question

我试图在rails中使用where检索一组项目。如果我检索all，我会看到：

2.2.2 :027 > JourneyLeg.all

JourneyLeg Load (0.2ms)  SELECT "journey_legs".* FROM "journey_legs"
=> #<ActiveRecord::Relation [
#<JourneyLeg id: 1, start_station: 24, end_station: 25, departure_time: "2000-01-01 06:37:00", arrival_time: "2000-01-01 06:45:00", journey: 6, created_at: "2015-07-25 11:32:42", updated_at: "2015-07-25 11:32:42">,
#<JourneyLeg id: 2, start_station: 25, end_station: 26, departure_time: "2000-01-01 06:46:00", arrival_time: "2000-01-01 06:50:00", journey: 6, created_at: "2015-07-25 11:32:42", updated_at: "2015-07-25 11:32:42">]>

现在我只想返回start_station为24的项目，因此我使用JourneyLeg.where(:start_station => 24)

2.2.2 :028 > JourneyLeg.where(:start_station => 24)
JourneyLeg Load (0.1ms)  SELECT "journey_legs".* FROM "journey_legs" WHERE "journey_legs"."id" = ?  [["start_station", 24]]
=> #<ActiveRecord::Relation []>

但由于某些原因，这是查询id而不是start_station（因此没有找到任何内容），但我不知道为什么。

更新1

感谢David的评论，我发现这个问题是由于我在名为start_station的模型上有一个属性，它是一个整数，但也是一个名为{{1}的has_one关系}}

start_station

如果我删除此关系或将其重命名，则以下内容可按预期方式使用各种建议：

has_one :start_station, :class_name => "Station", :primary_key => "start_station", :foreign_key => "id"

Answer 1

这应该基于Documentation of where

JourneyLeg.where({:start_station => 24})

我尝试使用我的本地应用程序的模型Article，跟随where的变体工作（Rails 4.2.2，Ruby 2.0.0p247）

变体1

irb(main):006:0> Article.where({id: 2})
  Article Load (1.0ms)  SELECT "articles".* FROM "articles" WHERE "articles"."id" = ?  [["id", 2]]
=> #<ActiveRecord::Relation [#<Article id: 2, title: "World", text: nil, created_at: "2015-07-25 21:09:16", updated_at: "2015-07-25 21:09:16">]>

变体2

irb(main):009:0> Article.where({:id => 2})
  Article Load (0.0ms)  SELECT "articles".* FROM "articles" WHERE "articles"."id" = ?  [["id", 2]]
=> #<ActiveRecord::Relation [#<Article id: 2, title: "World", text: nil, created_at: "2015-07-25 21:09:16", updated_at: "2015-07-25 21:09:16">]>

变体3

irb(main):010:0> Article.where(id: 2)
  Article Load (0.0ms)  SELECT "articles".* FROM "articles" WHERE "articles"."id" = ?  [["id", 2]]
=> #<ActiveRecord::Relation [#<Article id: 2, title: "World", text: nil, created_at: "2015-07-25 21:09:16", updated_at: "2015-07-25 21:09:16">]>

Answer 2

试试这个

JourneyLeg.where("start_station = '24'")

Rails不符合预期的行为

2 个答案: