PHP 菜单 - 如何递归删除父子项

Question

I am working on a data driven menu system in PHP /MySQL. I can't figure out how to delete menu items without leaving some of them orphaned.

All top level menu items have a zero (0) parent id value indicating that they are top level. My gridview displays all menus, top level and sub menu items and it allows multiple selection for delete.

The problem is that if one of the items selected in the gridview for delete is a top level menu item, all sub menus under it will become orphaned.

What is the general logic I need to implement?

Answer 1

Simply delete the child items when you delete some item. If you only have a 2 levels of depth this shouldn't be too much of a problem. If you can have X levels, then you'll have to recursively delete every child element for every element you delete.

Answer 2

The below class will work with as many childs as you can create(infinit)... so considering your mysql tabel is structered as(id,parent,name), all you need is a function that gets all items from current level, loop through each item and call recursively the function again to get child items for current loop id, each time keeping the ids found in an array to delete later, below is the full code in which I accomplished it using a class, but it can be done with a global array and function also.

//full class below comprising of 2 methods(functions)  
class menu_manager{

    //this is the function called with id, to initiate the recursive function below
    private function remove_menu_item($id){
        $ids_to_delete ="";
        //Zero global arrays for more than one call for this function get child menus id first in a an array
        $this->child_items_ids = array(0 => $id);
        $this->incrementby_one=0;
        //call recursive function with $id provided
        $this->get_array_of_child_ids($id); 
        //then createw ids for mysql IN Statment, foreach will create - 1,10,25,65,32,45,
        foreach($this->child_items_ids as $k=>$v ) $ids_to_delete.=$v.",";
        //Then we wrap it in around "(" and ")" and remove last coma to provide - (1,10,25,65,32,45)
        $ids_to_delete="(".substr($ids_to_delete, 0, -1).")";
        //then we Delete all id in one query only
        $remove = $this->db->query("DELETE FROM menu WHERE id IN $ids_to_delete ");
        if(!$remove) return false;
        else return true;
    } 

    /*this is the function that will be called as many times as a child is found,
this function is called inside of itself in the query loop*/ 

    private function get_array_of_child_ids($id){
        $query = $this->db->query("SELECT id,label,parent FROM menu WHERE parent='".$id."' ");
        if($query){
            if($query->num_rows > 0) { // if found any items
                while($list = $query->fetch_assoc()){ // we loop through each item
                    //increments array index by 1
                    $this->incrementby_one += 1;
                    //place current id in the array
                    $this->child_items_ids[$this->incrementby_one] = intval($list["id"]);
                    //and we call this function again for the current id
                    $this->get_array_of_child_ids($list["id"]);
                } // while closing
            } // second if closing
        }  //first if closing  
    }   // recursive function closing
}   // class closing

//to call the class you need:
$delete_items = new menu_manager;
$delete_items->remove_menu_item($id); //$id is the id for the item to be removed