title: getData of file in Symfony form
body: <p>I'm trying to retrieve the data from my csv file sent via the form but the result is null.</p>
  
  <p>Form :</p>
  
  <pre><code>$form = $this-&gt;createFormBuilder()
          -&gt;add('submitFile', FileType::class, array('label' =&gt; 'File to Submit'))
          -&gt;add('add', SubmitType::class)-&gt;getForm();
  $form-&gt;handleRequest($request);
  
  if ($form-&gt;isSubmitted() &amp;&amp; $form-&gt;isValid()) {
                      $filename = $form['submitFile']-&gt;getData();
                  dump($filename); exit; // i have result of null here
                  $header = NULL;
                  $data = array();
                  $delimiter = ';';
                  if (($handle = fopen($filename, 'r')) !== FALSE) {
                      while (($row = fgetcsv($handle, 1000, $delimiter)) !== FALSE) {
                          if(!$header) {
                              $header = $row;
                          } else {
                              $data[] = array_combine($header, $row);
                          }
                      }
                      fclose($handle);
                  }
                  return $data;
  </code></pre>
  
  <p>Am I doing something wrong?</p>