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POActiveRecord building for nested resource
 

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    <p>(NOTE: Source code here <a href="https://github.com/cthielen/dss-evote" rel="nofollow">https://github.com/cthielen/dss-evote</a>)</p> <p>I've got a simple voting application. A survey is the set of questions to vote on, a ballot is a per-user instance of their preferences, and the ballot has_many preferences, which again, are unique to each user. Here's the modeling:</p> <pre><code>class Ballot &lt; ActiveRecord::Base belongs_to :survey has_many :preferences end class Survey &lt; ActiveRecord::Base has_many :questions has_many :eligibilities has_many :ballots accepts_nested_attributes_for :questions, :allow_destroy =&gt; true attr_accessible :title, :description, :status, :deadline, :questions_attributes def owner Person.find(owner_id) end end class Question &lt; ActiveRecord::Base belongs_to :survey has_many :preferences end class Preference &lt; ActiveRecord::Base belongs_to :ballot belongs_to :question end </code></pre> <p>routes.rb only has this: resources :surveys do resources :ballots end</p> <p>/surveys/1 seems to work, even /surveys/1/ballots. /surveys/1/ballots/new is where I run into issues:</p> <p>in ballots_controller.rb:</p> <pre><code>def new @survey = Survey.find(params[:survey_id]) @ballot = @survey.ballots.build @survey.questions.count.times { @ballot.preferences.build } respond_to do |format| format.html # new.html.erb end end </code></pre> <p>(corresponding view)</p> <pre><code>&lt;%= form_for [@survey, @ballot] do |f| %&gt; &lt;%= f.fields_for @ballot.preferences do |preferences_fields| %&gt; &lt;% for question in @preferences_fields %&gt; &lt;p&gt; &lt;%= f.label question.question %&gt; &lt;%= radio_button(question.id, "preference", "Yes") %&gt; Yes &lt;%= radio_button(question.id, "preference", "No") %&gt; No &lt;%= radio_button(question.id, "preference", "Decline") %&gt; Decline &lt;/p&gt; &lt;% end %&gt; &lt;% end %&gt; &lt;div class="actions"&gt; &lt;%= f.submit "Vote" %&gt; &lt;/div&gt; &lt;% end %&gt; </code></pre> <p>Results in the error:</p> <pre><code>NoMethodError in Ballots#new Showing /Users/cthielen/Projects/Work/dss-evote/app/views/ballots/_form.html.erb where line #2 raised: undefined method `model_name' for Array:Class Extracted source (around line #2): 1: &lt;%= form_for [@survey, @ballot] do |f| %&gt; 2: &lt;% f.fields_for @ballot.preferences do |preferences_fields| %&gt; 3: &lt;% for question in @preferences_fields %&gt; 4: &lt;p&gt; 5: &lt;%= f.label question.question %&gt; </code></pre> <p>Now, it appears an array is being formed instead of proper instances of the class, but I'm at a loss for how to properly fix this.</p> <p>EDIT: I should mention the reason I'm attempting to build @ballot.preferences are that the preferences represent a person's answer, and the length of preferences may change from survey to survey. So if a survey has six questions, @ballot.survey.questions.length will be 6, and I need to create 6 blank @ballot.preferences, which will then be represented by form_for and hopefully saved properly using a RESTful Create.</p> <p>Thanks in advance for any help you can offer!</p>
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