title: How to pass additional (radio-buttons) parameters through rails form created with form_for?
body: <p>I have a form_for helper that creates an object for my <code>Image</code> model. It looks like this: </p>
  
  <pre><code>&lt;%= form_for :image, url: images_path do |f| %&gt; 
  
    &lt;p&gt;
      &lt;%= f.file_field :file %&gt; 
    &lt;/p&gt; 
  
    &lt;p&gt;
      &lt;input type="radio" name="index" value="1"&gt;1 
      &lt;input type="radio" name="index" value="2"&gt;2
      &lt;input type="radio" name="index" value="3"&gt;3
    &lt;/p&gt;
  
    &lt;p&gt;&lt;%= f.submit "submit" %&gt;&lt;/p&gt; 
  &lt;% end %&gt; 
  </code></pre>
  
  <p>After observing the params hash, the :file is getting passed as expected. I need the value in the radio buttons to be passed in this hash as well, or at the very least, I need to know what this value is in the <code>create</code> function of the Image controller. How can I pass this value through the params hash (or through some other way)?</p>