title: Generate URL (url_for) with Ruby On Rails
body: <p>How to generate urls for mails with an application in API mode?</p>
  
  <p>I want to generate a URL of type: "host/confirmation/token"?</p>
  
  <p>I tested:</p>
  
  <pre><code>&lt;%= url_for("confirm/#{@token}") %&gt;
  </code></pre>
  
  <p>Result:</p>
  
  <pre><code>confirm/JtuQW54DkZXtAnhm
  </code></pre>
  
  <p>But host are not present, how to put "host" inside ?</p>
  
  <p>I configured:</p>
  
  <pre><code>  config.action_mailer.default_url_options = {
       host: "lol.com"
    }
  </code></pre>