private function validateForm()
{
// set values
$charset = $this->getContainer()->getParameter('kernel.charset');
$searchTerm = \SpoonFilter::getPostValue('term', null, '');
$this->term = $charset == 'utf-8' ? \SpoonFilter::htmlspecialchars($searchTerm) : \SpoonFilter::htmlentities($searchTerm);
$this->length = (int) \SpoonFilter::getPostValue('length', null, 50);
// validate
if ($this->term == '') {
$this->output(self::BAD_REQUEST, null, 'term-parameter is missing.');
}
}