Error when using unserialize() in php when check isset of item array()?
<p>I have a sample code:</p>

<pre><code>$text = 'a:3:{s:2:"id";s:18:"nokiainternal_ver1";s:10:"user_agent";s:13:"NokiaInternal";s:9:"fall_back";s:13:"nokia_generic";}';
$text = unserialize($text);
if(isset($text['model_name'])) {
   $text['model_name'] = 'Nokia'; 
}
echo $text['model_name'];
echo $text['user_agent'];
</code></pre>

<p>But result error <code>Notice: Undefined index: model_name ...</code> How to fix it ?</p>
