如何在数组的父元素中获得返回的子元素

我必须PHP函数，返回父元素的所有子递归，但是，当我试图得到返回的子在其父在数组中，我收到错误或子刚刚被添加在数组的根级。我如何修改这个函数来插入子元素在它的父元素在子数组??

public function getAllChilds($Parent_ID, $level_identifier="", $start=true) { // get     all the childs of all the levels under a parent as a tree      
        $immediate_childs=$this->getImmediateChilds($Parent_ID,  $this-    >extra_condition, $this->order_by_phrase);
        if(count($immediate_childs)) {
            foreach($immediate_childs as $chld) {
                $chld[$this->item_list_field_name]=$level_identifier.$this->item_pointer.$chld[$this->item_list_field_name];
                array_push($this->all_childs,$chld);
                $this->getAllChilds($chld[$this->item_identifier_field_name], ($level_identifier.$this->level_identifier), false);
            }
        }
        if($start) {
            return $this->all_childs; 
        }
    } 
private function getImmediateChilds($parent_identifier_field_value, $extra_condition="", $order_by_phrase="") { // get only the direct/immediate childs under a parent 
    $sql="SELECT * FROM `".$this->db_table."` WHERE `".$this->parent_identifier_field_name."`='".$parent_identifier_field_value."' ".$extra_condition." ".$order_by_phrase;
    $res=mysql_query($sql);
    $childs=array();
    while($val=mysql_fetch_assoc($res)) {
        array_push($childs,$val);
    }
    return $childs; 
}

这一行是将子元素插入到数组中，但我希望将子元素插入到父元素中，并添加另一个名为children的数组元素，这是父元素中的目标数组，用于放置子返回元素..

array_push($this->all_childs,$chld);

请帮助! !这个函数的目标是最终返回一个多级数组树，它将被转换成JSON树。

是完整的类代码:

<?php   
class ParentChild { 
    //properties which hold database and table related information  : start     
    var $db_host;
    var $db_user;
    var $db_pass;
    var $db_database;
    var $db_table; 

    var $item_identifier_field_name;  //may be the primary key of the table : as decided by the db designer 
    var $parent_identifier_field_name; //the fileld name in the table which holds the value of the item_identifier_field_name any item's parent : as decided by the db designer
    var $item_list_field_name; //field name in the table whose value will be shown in the list or tree (like name or any id etc.) : as choosen by the programmer 
    var $extra_condition="";  //if any extra condition should be added with the query : as desided by the programmer 
    var $order_by_phrase="";  //if any order by phrase should be added with the query : as desided by the programmer 
    //properties which hold database and table related information  : end

    var $level_identifier = "  ";  //no. of level of any item as per the generated tree : it will appear number of level times before the item in the list/tree
    var $item_pointer = "|-"; 

    var $all_childs = array(); //contains the entire tree or list starting from a given root element
    var $item_path = array(); //contains the total path of a given element/node(the list of elements starting from the top level root node to the given element/node)
    public function getAllChilds($Parent_ID, $level_identifier="", $start=true) { // get all the childs of all the levels under a parent as a tree      
        $immediate_childs=$this->getImmediateChilds($Parent_ID,  $this->extra_condition, $this->order_by_phrase);
        if(count($immediate_childs)) {
            foreach($immediate_childs as $chld) {
                $chld[$this->item_list_field_name]=$level_identifier.$this->item_pointer.$chld[$this->item_list_field_name];
                array_push($this->all_childs,$chld);
                $this->getAllChilds($chld[$this->item_identifier_field_name], ($level_identifier.$this->level_identifier), false);
            }
        }
        if($start) {
            return $this->all_childs; 
        }
    } 
    private function getImmediateChilds($parent_identifier_field_value, $extra_condition="", $order_by_phrase="") { // get only the direct/immediate childs under a parent 
        $sql="SELECT * FROM `".$this->db_table."` WHERE `".$this->parent_identifier_field_name."`='".$parent_identifier_field_value."' ".$extra_condition." ".$order_by_phrase;
        $res=mysql_query($sql);
        $childs=array();
        while($val=mysql_fetch_assoc($res)) {
            array_push($childs,$val);
        }
        return $childs; 
    }
    public function getItemPath($item_id,$start=true){ //returns the total path of a given item/node(the list of elements starting from the top level root node to the given item/node)
        if($item_id != 0) {
            $sql="SELECT * FROM `".$this->db_table."` WHERE `".$this->item_identifier_field_name."`='".$item_id."' ";
            $res=mysql_query($sql);
            $itemdata=mysql_fetch_assoc($res);
            array_push($this->item_path,$itemdata); 
            if($itemdata[$this->parent_identifier_field_name]!=0) {
                $this->item_path=$this->getItemPath($itemdata[$this->parent_identifier_field_name],false);
            } 
            if ($start) {
                $this->item_path=array_reverse($this->item_path);
            }
        }
        return $this->item_path;
    }
    public function db_connect(){
        $conn = mysql_connect($this->db_host, $this->db_user, $this->db_pass); 
        if($conn) {
            mysql_select_db($this->db_database, $conn);
        } 
        return $conn;
    }
    public function db_disconnect(){
        mysql_close();
    }
} 
?>