Laravel parent/child relationship

Create a parent/child relationship within a model, based on a parent_id in the databast table

id name    parent_id
1 Group 1  NULL
2 Group 2  1

<?php // model

class Group extends Eloquent {

    public function parent()
    {
        return $this->belongsTo('group', 'parent_id');
    }

    public function children()
    {
        return $this->hasMany('group', 'parent_id');
    }
}

// Controller
$group = $this->group->with('children', 'parent')->find(1);
// Outputs:
/*
array (size=8)
  'id' => int 1
  'name' => string 'Group 1' (length=7)
  'parent_id' => null
  'children' => 
    array (size=1)
      0 => 
        array (size=5)
          'id' => int 2
          'name' => string 'Group 2' (length=7)
          'parent_id' => int 1
  'parent' => null
*/