Trouble with rails naming conventions

问题

I think I have followed the rails naming conventions in my app. But when I am in the terminal testing code I am coming across some errors that go against naming conventions. Here is my terminal session:

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'

Now when I try 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

From my models:

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

I am at a standstill, stuck, banging my head against the wall, etc. Any help would be fabulous.

Rails noobie here....as if this point is not obvious.....

回答1:

Noticed that you appear to be in IRB... Instead, I'd try to stay in the rails console when working with your active-record classes.

so start that with

bundle exec rails console

回答2:

What you need here is a junction table. See the association has_and_belongs_to_many.

The junction table will store the links between a certain Neighbourhood and a certain CtaTrain. Here, it's CtaLocation but if you don't plan to actually use this model, you could even not define it.

For instance, you can achieve it With three tables (neighbourhoods, cta_trains and cta_trains_neighbourhoods) and only two models like :

class Neighbourhood
  has_and_belongs_to_many :cta_trains
end

class CtaTrain
  has_and_belongs_to_many :neighbourhoods
end

来源：https://stackoverflow.com/questions/8553768/trouble-with-rails-naming-conventions

标签

ruby-on-rails

naming-conventions

has-many-through