Rails: Issue with multi-level has_many and undefined method

I'm getting an undefined method 'answers' error with this: @survey.questions.answers

Just running @survey.questions works as you'd expect.开发者_JS百科

Here's my model setup:

class Survey < ActiveRecord::Base
  has_many :questions

  accepts_nested_attributes_for :questions, :reject_if => lambda { |a| a[:text].blank? }, :allow_destroy => true
end

class Question < ActiveRecord::Base
  belongs_to :survey
  has_many :answers

  accepts_nested_attributes_for :answers, :reject_if => lambda { |a| a[:text].blank? }, :allow_destroy => true
end

class Answer < ActiveRecord::Base
  belongs_to :question
  has_many :responses
end

So, what am I doing wrong here? Each model has the correct _id field to make the association.

I'm running Rails 3.0.3. Also, here's the full trace:

>> @survey.questions.answers
NoMethodError: undefined method `answers' for #<Class:0x10375cc28>
    from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/base.rb:1008:in `method_missing'
    from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations/association_collection.rb:443:in `send'
    from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations/association_collection.rb:443:in `method_missing'
    from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/base.rb:1121:in `with_scope'
    from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations/association_proxy.rb:203:in `send'
    from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations/association_proxy.rb:203:in `with_scope'
    from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations/association_collection.rb:439:in `method_missing'
    from (irb):9

@survey.questions is a collection of questions.

try @survey.questions.first.answers

Of course, in your view, you could do:

<% @survey.questions.each do |question| %>
  <%= question.title %>
  <% question.answers.each do |answer| %>
    <%= answer.title %>
  <% end %>
<% end %>

@survey.questions.map(&:answers)