title: undefined method `stringify_keys!' ruby on rails
body: <p>I have this code:</p>
  
  <pre><code>def addcar
    @car = Car.new(params[:car])
    render :action =&gt; 'list'
  end
  
  &lt;% @allcars.each do |cell| %&gt;
    &lt;p&gt;
      &lt;%= link_to cell.to_s, :controller =&gt; 'car', :action =&gt; 'addcar', :car =&gt; cell.to_s %&gt;
    &lt;/p&gt;
  &lt;% end %&gt;
  </code></pre>
  
  <p>It's giving me this error:</p>
  
  <blockquote>
    <p>undefined method `stringify_keys!' for "Honda":String</p>
  </blockquote>
  
  <p>I don't understand what is wrong with <code>:car</code>.</p>