Symfony2: 3d to 2d. Display tree navigation menu in a select dropdown in SonataAdmin

Keys: SonataAdmin, Gedmo Tree nested type, Select Dropdown, use EntityManager in configureFormFields Admin page

I've lost 2 days bumping my head on a simple task - I needed to display simple dropdown combo box that will display Nested Gedmo Tree in a Sonata Admin form.

I've installed and get working - It's simple implementation of Gedmo\Tree type="nested" - exactly what I need for a simple menu navigation + it has ready Sonataadmin page to edit nodes.
The nice thing about this exact bundle is that it uses @Translatable, @Blameable, @Timestampable and this is all what I need - to be able to translate my menu, to see when and who updated the records.

After installing it I've noticed that 'path' is missing/empty event getting undefined notice.
I've dug around and found that I have to implement getpath() myself.
I did and created custom repository. I wasn't able to use childrenHierarchy directly in the Entity.

namespace Room13\NavigationBundle\Entity\Repository;
class NavigationNodeRepository extends \Gedmo\Tree\Entity\Repository\NestedTreeRepository{
function getFlatNodes($startNode = null, $options = null) {
if (is_null($options)) {
$options = array(
'decorate' => false,
'rootOpen' => '
    'rootClose' => '
'childOpen' => '
  • ',
    'childClose' => '
  • ',
    'nodeDecorator' => function($node) {
    return ''.$node['title'].'';
    $htmlTree = $this->childrenHierarchy(
    $startNode, / starting from root nodes /
    false, / load all children, not only direct /
    return $this->ToFlat($htmlTree, ' » ');

    function ToFlat($node, $sep = ' > ', $path = '') {
    $els = array();
    foreach ($node as $id => $opts) {
    $els[$opts['id']] = $path . $opts['title'];
    if (isset($opts['__children']) && is_array($opts['__children']) && sizeof($opts['__children'])) {
    $r = $this->ToFlat($opts['__children'], $sep, ($path . $opts['title'] . $sep));
    foreach($r as $id => $title) {
    $els[$id] = $title;
    return $els;

    After implementing it I've had to find a way so I can display result of this for root node in a flat select box in SonataAdminPage so user can select from a dropdown where the content should show.
    Well.. it turned out that entity type is impossible to be used because it can't call the method from CustomRepo, just the native Entity methods.
    I ended up using simple 'select' type like this:

    $em = $this->modelManager->getEntityManager('Room13NavigationBundle:NavigationNode');
    $tree = $em->getRepository('Room13NavigationBundle:NavigationNode')->getFlatNodes();
    ->add('menu', 'choice', array(
    'label' => 'Place in menu',
    'empty_value' => 'Select menu',
    'choices' => $tree,