title: How to display checked value for radio button collection
body: <p>Question about Rails 5 and <code>collection_radio_buttons</code>. </p>
  
  <p>How do you have it display the checked value of a radio input when you try and edit the form?</p>
  
  <pre><code>&lt;%= collection_radio_buttons(:post, :category_id, Category.all, :id, :name) do |b| %&gt;
    &lt;div class="radio"&gt;
       &lt;%= b.label do %&gt;
         &lt;%= b.radio_button + b.text %&gt;
       &lt;% end %&gt;
    &lt;/div&gt;
  &lt;% end %&gt;
  </code></pre>
  
  <p>With select box <code>f.collection_select</code> it remembers the value but not with <code>collection_radio_buttons</code></p>
  
  <p>My routes file is as follows</p>
  
  <h1>Routes</h1>
  
  <p>resources :posts, as: :entries</p>