Mongolid\Model\DocumentEmbedder::attach PHP Метод

    public function attach($parent, string $field, &$entity) : bool
    {
        $fieldValue = (array) $parent->{$field};
        $newId = $this->getId($entity);
        foreach ($fieldValue as $id) {
            if ($id == $newId) {
                return true;
            }
        }
        $fieldValue[] = $newId;
        $parent->{$field} = $fieldValue;
        return true;
    }