#411 new
Andy Gregorowicz

polymorphic_path breaks on uncountable resources

Reported by Andy Gregorowicz | June 13th, 2008 @ 01:59 PM

It seems that passing an uncountable resource to polymorphic_path and associated methods causes an exception to be thrown.

This causes an exception for me on Rails 2.1 under Ruby 1.8.6

Migration 

create_table :sheep do |t|
  t.string :name

  t.timestamps
end

Model 

class Sheep < ActiveRecord::Base
end

Routes 

ActionController::Routing::Routes.draw do |map|
  map.resources :sheep, :singular => :sheep_instance

  map.connect ':controller/:action/:id'
  map.connect ':controller/:action/:id.:format'
end

$ script/console

Loading development environment (Rails 2.1.0)

>> sheep = Sheep.create(:name => 'Dolly')

=> #

>> app.polymorphic_path(sheep)

NoMethodError: You have a nil object when you didn't expect it!

The error occurred while evaluating nil.to_sym

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/routing/route.rb:145:in `extra_keys'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/routing/route.rb:145:in `map'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/routing/route.rb:145:in `extra_keys'

from generated code (/Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/routing/route.rb:45):3:in `generate'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/routing/route.rb:122:in `generate'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/routing/route_set.rb:337:in `generate'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/url_rewriter.rb:131:in `rewrite_path'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/url_rewriter.rb:110:in `rewrite_url'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/url_rewriter.rb:88:in `rewrite'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/integration.rb:218:in `url_for'

from (eval):17:in `sheep_path'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/polymorphic_routes.rb:101:in `send!'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/polymorphic_routes.rb:101:in `polymorphic_url'

from /Library/Ruby/Gems/1.8/gems/actionpack-2.1.0/lib/action_controller/polymorphic_routes.rb:108:in `polymorphic_path'

from (irb):2

Comments and changes to this ticket

  • Andy Gregorowicz

    Andy Gregorowicz June 19th, 2008 @ 10:27 AM

    The problem seems to be that RecordIdentifier is used to determine the singular class name, which is then used to generate the named route call. So for instance, when calling 

    
polymorphic_path(sheep)

    RecordIdentifier will be called and come up with the singular class name of sheep and the following route will be called. 

    
sheep_path(sheep)

    When it should be 

    
sheep_instance_path(sheep)

    RecordIdentifier doesn't know about the :singular option passed into the route definition. I'm not sure what would be the best way to fix this... Any suggestions?

  • Zach Carter

    Zach Carter July 30th, 2008 @ 03:39 PM

      • → Tag changed from “” to “2.1 actionpack bug”

    Currently I patch RecordIdentifier to add _instance to the class name if the singular and plural are the same: 

    module ActionController  
  module RecordIdentifier
    # Returns the singular class name of a record or class. Examples:
    #
    #   singular_class_name(post)             # => "post"
    #   singular_class_name(Highrise::Person) # => "highrise_person"
    #   singular_class_name(sheep)             # => "sheep_instance"
    def singular_class_name(record_or_class)
      model_name = model_name_from_record_or_class(record_or_class)
      model_name.singular + (model_name.singular == model_name.plural ? '_instance':'')
    end
  end
end

    Still looking for a proper fix.

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