public function containsOne($field, $model)
{
if (is_array($field) && $field[0]) {
$field['name'] = $field[0];
unset($field[0]);
}
if ($e = $this->hasElement(is_string($field) ? $field : $field['name'])) {
$e->destroy();
}
$this->add('Relation_ContainsOne', $field)->setModel($model);
}