private function check_fields(array $data)
{
$ruleset = $this->validation_rules();
$mismatch = array_diff_key($data, $ruleset);
$fields = array_keys($mismatch);
foreach ($fields as $field) {
$this->errors[] = array('field' => $field, 'value' => $data[$field], 'rule' => 'mismatch', 'param' => null);
}
}