How to get and set value of chat request form filed using hooks

Content

In chat_launch.php page ,I add a custom field named mobile_phone_number of contact to the form,I want to check if exist contact with the mobile number before submit the chat request form. So I used pre page render hooks,in custom model,How can i get mobile number value of chat request form , when I logmessage $hookdata['data'],but found array is empty,I want to get and set value to the page form field.

Can you give some advices for me ? thank you.

Version

1

Code Snippet

             function checkMobile($hookdata)
    {  
		$CI = get_instance(); 
        $url = $_SERVER['REQUEST_URI']; //app/chat/chat_launch/chat_data/cV9pZD0xJnN0YXRlPTEwJiZoYXNoPTE1Mjk2NTA3MTc2MzNybHJpbXk./request_source/7
        $page = $CI->page;  //chat/chat_launch
	if( $page=='chat/chat_launch'){
		$chat_launch=$hookdata['data'];
		logMessage($hookdata['data']);
		//get contact
		$mobile='';
}
}