Recursive function PHP in MODx / problem

<?php

function getTree2($parent2) {

    $path = MODX_CORE_PATH . 'components/pepish2/';
    $result = $modx->addPackage('pepish2',$path . 'model/','pp_');
  
  if($result){
  $g = $modx->newQuery('Category');
  $g->where(array(
    'parent_id' => $parent2,
));

  $trees = $modx->getCollection('Category',$g);
}  
  
$pole2 = array();
  
foreach ($trees as $tre) {
	$pole2[] = $tre->get('category_id');
	$pole2 = array_merge($pole2, getTree2($tre->get('category_id')));
  echo '$pole2'.$pole2.'<br>';
}

return $pole2;
}


$iii = '9';  //this is only sample number
$seznam_kategorii = getTree2($iii);

echo '<br>$seznam_kategorii= '.$seznam_kategorii.'<br>';

$seznam_kategorii[] = $iii;
$seznam_kategorii_retezec = implode(',', $seznam_kategorii);
echo '<br>Seznam kategorií:  '.$seznam_kategorii_retezec.'<br>';

<?php
function getTree2($parent2) {

  $database3="databasename";
mysql_connect ("mysql.server", "user", "password");
mysql_query('SET NAMES utf8'); 
@mysql_select_db($database3) or die( "Unable to select database");
  
  $result2 = mysql_query('SELECT * FROM category WHERE parent_id='.$parent2.' ORDER BY name asc');

  $pole2 = array();
  while ($row2 = mysql_fetch_assoc($result2)) {
    $pole2[] = $row2['id'];
//    array_merge($pole2, getTree2($row2['id']));
$pole2 = array_merge($pole2, getTree2($row2['id']));
  }

  return $pole2;
}



$iii = 9;
$seznam_kategorii = getTree2($iii);

$seznam_kategorii[] = $iii;
$seznam_kategorii_retezec = implode(',', $seznam_kategorii);
echo '<br>Seznam kategorií:  '.$seznam_kategorii_retezec.'<br>';

<?php

function getTree2($parent2)
{
    global $modx;

    $g = $modx->newQuery('Category');
    $g->where(array('parent_id' => $parent2));
    $pole2 = array();
    if ($trees = $modx->getCollection('Category', $g)) {
        foreach ($trees as $tre) {
            $pole2[] = $tre->get('category_id');
            $pole2 = array_merge($pole2, getTree2($tre->get('category_id')));
            echo '$pole2' . $pole2 . '';
        }
    }

    return $pole2;
}

$path = MODX_CORE_PATH . 'components/pepish2/';
$result = $modx->addPackage('pepish2', $path . 'model/', 'pp_');

if ($result) {
    $iii = '9'; //this is only sample number
    $seznam_kategorii = getTree2($iii);
}


echo '$seznam_kategorii= ' . $seznam_kategorii . '';

$seznam_kategorii[] = $iii;
$seznam_kategorii_retezec = implode(',', $seznam_kategorii);
echo 'Seznam kategorií:  ' . $seznam_kategorii_retezec . '';

if($result){
  $f = $modx->newQuery('Galerie');
  $f->where(array(
      'kategorie:IN' => array($seznam_kategorii_retezec),
));
  $f->sortby('galerie_id','ASC');

  $vypis = $modx->getCollection('Galerie',$f);
}

 $f->where(array('kategorie:IN' => $seznam_kategorii));

<?php
function getTree($parent) {  
  global $modx;
    $path = MODX_CORE_PATH . 'components/pepish2/';
    $result = $modx->addPackage('pepish2',$path . 'model/','pp_');  
  if($result){
  $g = $modx->newQuery('Category');
  $g->where(array(
    'parent_id' => $parent,
));
  $trees = $modx->getCollection('Category',$g);
}  
$pole = array();  
foreach ($trees as $tre) {
	$pole[] = $tre->get('category_id');
	$pole = array_merge($pole, getTree($tre->get('category_id')));
}
return $pole;
}




$path = MODX_CORE_PATH . 'components/pepish2/';
$result = $modx->addPackage('pepish2',$path . 'model/','pp_');

echo '<form action="[[~[[*id]]]]" method="post" class="form">
<select name="sel_cat" size="1">';

if($result){
  $d = $modx->newQuery('Category');
  $d->where(array(
    'view' => '1',
));
  $d->orCondition(array(
   'view' => '2',
));
  $d->sortby('category_id','ASC');
//$d->limit('16');

  $seznam = $modx->getCollection('Category',$d);
}

foreach ($seznam as $sez) {
	echo '<option value='.$sez->get('category_id').'>'.$sez->get('name').'</option>';
}

echo '</select>
<input type="submit" value="odeslat">
</form><br><hr>';

 $d->prepare();
  echo 'SQL QUERY:<br><font face="Tahoma" size="-2" color="#FFFF99">'.$d->toSql().'</font><br><hr>';


if (!isset($_POST['sel_cat'])) $_POST['sel_cat'] = '0';
$a = ($_POST['sel_cat']);



echo 'ID zvolené kategorie je: '.$a.'<br>';

if($result){
  $e = $modx->newQuery('Category');
  $e->where(array(
    'category_id' => $a,
));
  $seze = $modx->getCollection('Category',$e);
}

foreach ($seze as $se) {
	echo 'Vybraná kategorie je: '.$se->get('name').'<hr>';
}


$iii = $a;
$seznam_kategorii = getTree($iii);
$seznam_kategorii[] = $iii;
$seznam_kategorii_retezec = '\''.implode('\',\'', $seznam_kategorii).'\'';
echo 'Seznam kategorií celé vybrané větve:  <br>'.$seznam_kategorii_retezec.'<br><hr>';


if($result){
  $f = $modx->newQuery('Galerie');
  $f->where(array('kategorie:IN' => $seznam_kategorii));
  $f->sortby('galerie_id','ASC');
//$f->limit('16');
  $vypis = $modx->getCollection('Galerie',$f);
}
    
$f->prepare();
 echo 'SQL QUERY:<br><font face="Tahoma" size="-2" color="#FFFF99">'.$f->toSql().'</font><br><hr>';
 echo 'Celkový počet nalezených záznamů: '.count($vypis).'<br><hr>';    
    
echo '<div id="db">
<table align="center" width="96%" height="auto" border="1" bordercolor="#FFCC00" bgcolor="#008080">';
echo '<tr class="tab"><th>ID</th><th>Name CZ</th><th>Name Latin</th><th>Místo</th><th>Datum snímku</th><th>Cesta k fotografii</th></tr>';

foreach ($vypis as $vyp) {
  echo '<tr>';
  echo '<td> '.$vyp->get('galerie_id').'</td>'."\n";
  echo '<td> '.$vyp->get('name_cz').'</td>'."\n";
  echo '<td> '.$vyp->get('name_lat').'</td>'."\n";
  echo '<td> '.$vyp->get('kde').'</td>'."\n";
  echo '<td> '.$vyp->get('kdy').'</td>'."\n";
  echo '<td> '.$vyp->get('path_large').'</td>'."\n";
  echo '</tr>';
}

echo '</table>
</div> <!-- end db -->';