<?php

class App_User_Group_Admin_Obj extends Qs_Db_Obj
{
    protected $_hasFilter = false;
    protected $_tableAlias = 'UserGroup';

    protected function _getFromColumns()
    {
        $columns = parent::_getFromColumns();
        $columns['amount'] = new Zend_Db_Expr('(' . $this->_getMemberAmountSubselect() . ')');
        return $columns;
    }

    protected function _getMemberAmountSubselect()
    {
        $select = $this->_db->select();
        $select->from($this->_getPair('User'), 'COUNT(*)');
        $select->where('`' . $this->_tableAlias . '`.`id` = `User`.`groupId`');
        return $select;
    }

    protected function _getFromDbColumns()
    {
        $columns = parent::_getFromDbColumns();
        $columns['amount'] = new Zend_Db_Expr('(' . $this->_getMemberAmountSubselect() . ')');
        return $columns;
    }

    public function delete()
    {
        if ($this->getData('amount') > 0) {
            $this->_addError('Group \'' . $this->getData('title') . '\' is not empty and can\'t be removed.');
            return false;
        }
        return parent::delete();
    }
}