title: HTML Form - Button to submit empty string or default text
body: <p>Is it possible to have a button on my HTML template which sends an empty string to the handler? E.g. I used this form which has a text box:</p>
  
  <pre><code>&lt;form method="POST" action="/data"&gt;
  &lt;p&gt;City name: &lt;input type="text" name="city_choice"&gt;&lt;/p&gt;
  &lt;input type="submit" value="Submit"&gt;&lt;/form&gt;&lt;br&gt;&lt;/html&gt;
  </code></pre>
  
  <p>This gives a text box with a submit button, is it possible to just have a submit button which sends either an empty string or some default text? </p>