title: Flask WTF forms adding a glyphicon in a form field
body: <p>I have a Flask Wtf form as follows:</p>
  
  <pre><code>class URL_Status(Form):
      url = URLField("Enter URL",
                         validators=[url(), DataRequired()],
                         render_kw={"placeholder": "http://www.example.com"},)
      submit = SubmitField('Search', render_kw={"onclick": "loading()"})
  </code></pre>
  
  <p>now I would like to add a bootstrap glyphicon in the input filed i.e. 'url'. As far as I know from this <a href="https://stackoverflow.com/questions/18838964/add-bootstrap-glyphicon-to-input-box">link</a>. We need to write the code as follows:</p>
  
  <pre><code>&lt;div class="form-group has-feedback"&gt;
      &lt;label class="control-label"&gt;Username&lt;/label&gt;
      &lt;input type="text" class="form-control" placeholder="Username" /&gt;
      &lt;i class="glyphicon glyphicon-user form-control-feedback"&gt;&lt;/i&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>When I call the form in HTMl my html creates all the code except this line:</p>
  
  <pre><code>&lt;i class="glyphicon glyphicon-user form-control-feedback"&gt;&lt;/i&gt;
  </code></pre>
  
  <p>Any suggestions how can I add this line from my class 'URL_Status' so that I am able to see a glyphicon with my input field. Thanks</p>