Converting Mysql Select to Multidimensional Array of Directory Structure independent of levels using PHP -

so have select statement returns 3 values db:

• folder id,
• folder name,
• parent id.

if folder has no parent returns null parent id.

using data have split results 2 arrays.

one named $tree, used "directory tree", , firstly contain parent folders have parent id set null... , named $children, contains other folders children.

with these attempting create multidimensional array($tree) use display file structure user using php/html. ideally use recursion allow not knowing how deep directory goes.

i trying following no success , after whole day thinking feel stuck (function find children gets called function getdirtree further down):

    // should recursive function. takes 2 arrays argument.     // returns $tree() multiple dimension array       function findchildren($tree, $children){     // tree has 2 parents in first run     foreach($tree $folder){         $temparray = array();         // children has 4         foreach($children $child){             if ($child['parentid'] === $folder['folderid']){                 array_push($temparray, $child);                 if(($childkey = array_search($child, $children)) !== false) {                     unset($children[$childkey]);                 }             }         }         if(($parentkey = array_search($tree, $folder)) !== false) {             array_push($children[$parentkey],$temparray);         }     } // need have sort of recursion in function //    if (!empty($children)){ //        findchildren($tree, $children); //    } }  // takes userid int , returns multi dimensional array representing users folder structure. function getdirtree($userid){     global $mysqli;      $children = array();     $tree = array();      if($folders = $mysqli->prepare("select folders.id, folders.name, child_of_folder.parent_id                                     child_of_folder                                     right join folders                                     on  (child_of_folder.child_id = folders.id)                                     folders.user_id = ?;")) {         // bind parameters...  s string , variable $name bound.         if ($folders->bind_param("i", $userid)) {             // execute query             if ($folders->execute()) {                 // store results                 if($folders->store_result()){                     // bind results                     if($folders->bind_result($folderid, $foldername, $parentid)) {                         // fetch results                         while ($folders->fetch()) {                             if ($parentid === null) {                                 array_push($tree, array('folderid' => $folderid, 'foldername' => $foldername, 'parentid' => $parentid));                             } else {                                 array_push($children, array('folderid' => $folderid, 'foldername' => $foldername, 'parentid' => $parentid));                             }                         }                      } else {                         $hasfolder = null;                     }                 } else {                     // if there no values store return false                     $hasfolder = null;                 }             } else {                 // if there problem executing statement return null                 $hasfolder = null;             }         } else {             // if there problem binding statement return null             $hasfolder = null;         }     } else {         // if there problem preparing statement return null         $hasfolder = null;     }      if(!empty($children)){         findchildren($tree, $children);     }     $folders->free_result();     $mysqli->close();      return $tree;    } 

output of $tree , $children before being passed findchildren():

children array before findchildren  array (     [0] => array         (             [folderid] => 2             [foldername] => home             [parentid] => 1         )      [1] => array         (             [folderid] => 3             [foldername] => account             [parentid] => 2         )      [2] => array         (             [folderid] => 4             [foldername] => bill             [parentid] => 2         )      [3] => array         (             [folderid] => 6             [foldername] => work             [parentid] => 2         )  )  tree array before findchildren  array (     [0] => array         (             [folderid] => 1             [foldername] => work             [parentid] =>          )      [1] => array         (             [folderid] => 5             [foldername] => hello             [parentid] =>          )  ) 

i think should work. changed xml structure instead of arrays since xml structure easier handle espcially when doing recursive. have taken assumptions, example $children array contains children in db. hope were looking for.

 function getfolderstructure($userid)   {    //global variable    $xml = new domdocument();     $xml->formatoutput = true;      $element = $xml->createelement($userid);    $element->nodevalue = '';      //get top level folders.     getdirtree($userid);     //goes through top level folders.     foreach($tree $toplevelfolder)    {        findchildren($element, $toplevelfolder);     }     $xml->appendchild($element);      return $xml;     }    //prob need use $this->xml   function findchildren(&$element, $folder)  {       if(is_array($folder) && isset($folder["folder_name"]) && isset($folder["folderid"]))    {        $folder = $xml->createelement($folder["folder_name"], "");          $folderidattribute = $xml->createattribute("folderid");          $folderidattribute->value = $folder["folderid"];          $folder-appendchild($folderidattribute);         if(isset($folder["parentid"]) && !empty($folder["parentid"]))        {            $parentidattribute = $xml->createattribute("parentid");              $parentidattribute->value = $folder["parentid"];              $folder->appendchild($folder);        }          foreach(findchildrenarray($folder['folderid']) $child)        {            findchildren($folder, $child);         }         $element->appendchild($folder);     } }  function findchildrenarray($folderid) {    $retarray = array();      foreach($children $child)    {        if(isset($child["parentid"]) && $child["parentid"] == $folderid)        {            array_push($retarray, $child);         }    } }