protected function mergeRules()
    {
        $rules = static::$rules;
        $output = array();

        if ($this->exists)
            $merged = array_merge_recursive($rules['save'], $rules['update']);
        else
            $merged = array_merge_recursive($rules['save'], $rules['create']);

        foreach ($merged as $field => $rules)
        {
            if (is_array($rules))
                $output[$field] = implode("|", $rules);
            else
                $output[$field] = $rules;
        }

        $this->mergedRules = $output;
    }