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POMethod becomes nil after an ajax response?
 

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    <p>The following code does the following: If the user, <strong>voted up</strong> show him a <em>delete vote</em> form and a <em>vote down form</em>. If the user <strong>voted down</strong>, show him a <em>vote up form</em> and the <em>delete vote form</em>. Otherwise just show the <em>vote up and vote down form</em> (I omitted some of the code so the question doesn't get too long).</p> <p><img src="https://i.stack.imgur.com/xwYwZ.png" alt="enter image description here"></p> <p>(scenario: user voted down):</p> <p><strong>posts_controller.rb:</strong></p> <pre><code> def show @post = Post.find(params[:id]) @replies = @post.replies.paginate(page: params[:page]) @reply = @post.replies.build @vote = Vote.new store_location end </code></pre> <p><strong>votes_controller.rb:</strong></p> <pre><code>class VotesController &lt; ApplicationController before_filter :signed_in_user def create @votable = find_votable # Destroy the vote first in case the user already voted if already_voted? @vote = @votable.votes.find_by_user_id(current_user.id) @vote.destroy end @vote = @votable.votes.build(params[:vote]) @vote.user_id = current_user.id @votable.save respond_to do |format| format.html { redirect_back } format.js end end def destroy @votable = find_votable @vote = @votable.votes.find_by_user_id(current_user.id) @vote.destroy @votable.reload respond_to do |format| format.html { redirect_back } format.js end end private def find_votable params.each do |name, value| if name =~ /(.+)_id$/ return $1.classify.constantize.find(value) end end nil end def already_voted? @votable.votes.exists?(:user_id =&gt; current_user.id) end end </code></pre> <p><strong>posts/vote_form</strong></p> <pre><code>&lt;div class="vote-form"&gt; &lt;% if @post.votes.exists?(:user_id =&gt; current_user.id) %&gt; &lt;% if @post.votes.find_by_user_id(current_user.id).polarity == -1 %&gt; &lt;%= form_for ([@post, @vote]), remote: true do |f| %&gt; &lt;%= f.hidden_field :polarity, value: 1 %&gt; &lt;div class="form-actions"&gt; &lt;%= button_tag type: :submit, class: "btn btn-small vote" do %&gt; &lt;i class="icon-thumbs-down"&gt;&lt;/i&gt; Vote up &lt;% end %&gt; &lt;/div&gt; &lt;% end %&gt; &lt;%= form_for ([@post, @post.votes.find_by_user_id(current_user.id)]), method: :delete, remote: true do |f| %&gt; &lt;div class="form-actions"&gt; &lt;%= button_tag type: :submit, class: "btn btn-small btn-primary unvote" do %&gt; &lt;i class="icon-thumbs-up"&gt;&lt;/i&gt; Vote down &lt;% end %&gt; &lt;/div&gt; &lt;% end %&gt; &lt;% end %&gt; </code></pre> <p><strong>votes/create.js:</strong></p> <pre><code>$('#&lt;%= @votable.class.name.downcase %&gt;-&lt;%= @votable.id %&gt; .vote-form').html( "&lt;%= escape_javascript(render('shared/delete_vote')) %&gt;" ); </code></pre> <p><strong>shared/_delete_vote.html.erb:</strong></p> <pre><code>&lt;% if @votable.votes.find_by_user_id(current_user.id).polarity == -1 %&gt; &lt;%= form_for ([@votable, @votable.votes.new]), remote: true do |f| %&gt; &lt;div class="form-actions"&gt; &lt;%= button_tag type: :submit, class: "vote-down btn btn-small" do %&gt; &lt;i class="icon-thumbs-up"&gt;&lt;/i&gt; Vote up &lt;% end %&gt; &lt;/div&gt; &lt;% end %&gt; &lt;%= form_for ([@votable, @vote]), method: :delete, remote: true do |f| %&gt; &lt;div class="form-actions"&gt; &lt;%= button_tag type: :submit, class: "vote-up btn btn-small btn-primary" do %&gt; &lt;i class="icon-thumbs-up"&gt;&lt;/i&gt; Vote down &lt;% end %&gt; &lt;/div&gt; &lt;% end %&gt; &lt;% end %&gt; </code></pre> <p>So, now everything works fine, except that I get this error when I click <em>vote down</em>, and then <em>vote up</em> right after (without refreshing the page):</p> <blockquote> <pre><code>ActionView::Template::Error (undefined method `polarity' for nil:NilClass): 1: &lt;% if @votable.votes.find_by_user_id(current_user.id).polarity == 1 %&gt; 2: &lt;%= form_for ([@votable, @vote]), method: :delete, remote: true do |f| %&gt; </code></pre> </blockquote> <p>What could be the problem?</p> <p><strong>EDIT:</strong></p> <p>I realized that the line in the error message is the problem (not <code>@votable</code>):</p> <pre><code>&lt;% if @votable.votes.find_by_user_id(current_user.id).polarity == 1 %&gt; </code></pre> <p>Strange, I thought it was the same as </p> <pre><code>&lt;% if @post.votes.find_by_user_id(current_user.id).polarity == 1 %&gt; </code></pre>
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    1. USalexchenco
    1. USalexchenco
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      1. POMethod becomes nil after an ajax response?
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      1. VTUpMod
    1. COAre you passing the CSRF token in the ajax call?
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      1. POMethod becomes nil after an ajax response?
      1. USTrent Earl
    2. CO@peterpan I'm not sure what's that, so maybe I'm not.
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      1. POMethod becomes nil after an ajax response?
      1. USalexchenco
 

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