gistfile1.txt

$serializer = $this->container->get('jms_serializer');
                $xml=$serializer->serialize($personForm, "xml"); //also for json


{"children":{"firstName":{"children":{"condition_pattern":{},"text":{}}},"surname":{"children":{"condition_pattern":{},"text":{}}},"isActor":{},"dateOfBirth":{},"eyeColor":{},"hairColor":{},"adressData":{"children":{"street":{"children":{"condition_pattern":{},"text":{}}},"city":{"children":{"condition_pattern":{},"text":{}}},"country":{}}},"adminAdressData":{"children":{"street":{"children":{"condition_pattern":{},"text":{}}},"city":{"children":{"condition_pattern":{},"text":{}}},"country":{}}}}}

<?xml version="1.0" encoding="UTF-8"?>
<form name="person_filter">
  <errors/>
  <form name="firstName">
    <errors/>
    <form name="condition_pattern">
      <errors/>
    </form>
    <form name="text">
      <errors/>
    </form>
  </form>
  <form name="surname">
    <errors/>
    <form name="condition_pattern">
      <errors/>
    </form>
    <form name="text">
      <errors/>
    </form>
  </form>
  <form name="isActor">
    <errors/>
  </form>
  <form name="dateOfBirth">
    <errors/>
  </form>
  <form name="eyeColor">
    <errors/>
  </form>
  <form name="hairColor">
    <errors/>
  </form>
  <form name="adressData">
    <errors/>
    <form name="street">
      <errors/>
      <form name="condition_pattern">
        <errors/>
      </form>
      <form name="text">
        <errors/>
      </form>
    </form>
    <form name="city">
      <errors/>
      <form name="condition_pattern">
        <errors/>
      </form>
      <form name="text">
        <errors/>
      </form>
    </form>
    <form name="country">
      <errors/>
    </form>
  </form>
  <form name="adminAdressData">
    <errors/>
    <form name="street">
      <errors/>
      <form name="condition_pattern">
        <errors/>
      </form>
      <form name="text">
        <errors/>
      </form>
    </form>
    <form name="city">
      <errors/>
      <form name="condition_pattern">
        <errors/>
      </form>
      <form name="text">
        <errors/>
      </form>
    </form>
    <form name="country">
      <errors/>
    </form>
  </form>
</form>