Question

我想我已经遵循了应用中的rails命名约定。但是当我在终端测试代码中时，我遇到了一些违反命名约定的错误。这是我的终端会议：

irb(main):010:0> a = _
=> #<Neighborhood id: 24, name: "Lincoln Park", created_at: "2011-12-03 20:29:00", updated_at: "2011-12-03 21:08:47", minlat: 41.91092, maxlat: 41.925658, minlng: -87.648761, maxlng: -87.636117>
irb(main):011:0> a.cta_trains
NoMethodError: undefined method `cta_trains' for #<Neighborhood:0x007fd666ee61e8>
    from /usr/local/Cellar/ruby/1.9.2-p290/lib/ruby/gems/1.9.1/gems/activemodel-3.1.1/lib/active_model/attribute_methods.rb:385:in `method_missing'

现在当我尝试a.CtaTrains：

irb(main):012:0> a.CtaTrains
  CtaTrain Load (0.4ms)  SELECT "cta_trains".* FROM "cta_trains" INNER JOIN "cta_locations" ON "cta_trains"."id" = "cta_locations"."CtaTrain_id" WHERE "cta_locations"."neighborhood_id" = 24
SQLite3::SQLException: no such column: cta_locations.CtaTrain_id: SELECT "cta_trains".* FROM "cta_trains" INNER JOIN "cta_locations" ON "cta_trains"."id" = "cta_locations"."CtaTrain_id" WHERE "cta_locations"."neighborhood_id" = 24
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: cta_locations.CtaTrain_id: SELECT "cta_trains".* FROM "cta_trains" INNER JOIN "cta_locations" ON "cta_trains"."id" = "cta_locations"."CtaTrain_id" WHERE "cta_locations"."neighborhood_id" = 24

从我的模特：

class Neighborhood < ActiveRecord::Base

  has_many :cta_trains, :through => :cta_locations
  has_many :cta_locations, :foreign_key => :neighborhood_id

end 

class CtaTrain < ActiveRecord::Base

  has_many :neighborhoods, :through => :cta_locations
  has_many :cta_locations, :foreign_key => :cta_train_id

end

class CtaLocation < ActiveRecord::Base

  belongs_to :neighborhood
belongs_to :cta_train

end

我处于停滞状态，陷入困境，头撞在墙上等等。任何帮助都会很棒。

Rails noobie在这里....好像这一点并不明显.....

Answer 1

注意到您似乎在IRB中...相反，我在使用您的活动记录类时会尝试留在rails控制台中。

所以用

开始吧

bundle exec rails console

Answer 2

这里需要的是一个联结表。请参阅关联has_and_belongs_to_many。

联结表将存储某个Neighbourhood和某个CtaTrain之间的链接。在这里，它是CtaLocation但如果你不打算实际使用这个模型，你甚至可以不定义它。

例如，您可以通过三个表（邻域，cta_trains和cta_trains_neighbourhoods）实现它，并且只有两个模型：

class Neighbourhood
  has_and_belongs_to_many :cta_trains
end

class CtaTrain
  has_and_belongs_to_many :neighbourhoods
end

有关rails命名约定的问题

2 个答案: