telegram callback_data is null in update array - php

Question

I'm trying to make responce to user press inline_button2, after inline_keyboard apper in chat and I click on inline_button2 I suppose object callback_data have data with "callback_data"=>'inline2' but callback_data is null
see screenshot
$access_token = '...';
$api = 'https://api.telegram.org/bot' . $access_token;
$content = file_get_contents("php://input");
$update = json_decode($content, TRUE);
$callback_query = $update['CallbackQuery'];
$callback_data = $callback_query['data'];
$message = $update["message"];
$text = $message["text"];
$chatId = $message["chat"]["id"];
if (!isset($chatId)) {exit;}
switch($callback_data){
case 'inline2':
sendMessage($chatId, "inline2 pressed",null);
break;
default:
sendMessage($chatId, var_export($callback_query,TRUE),null);
break;
}
switch($text) {
case 'inline':
$inline_button1 = array("text"=>"inline1","url"=>"http://google.com", "callback_data"=>'inline1');
$inline_button2 = array("text"=>"inline2","callback_data"=>'inline2');
$inline_keyboard = array(array($inline_button1,$inline_button2));
$keyboard=array("inline_keyboard"=>$inline_keyboard);
sendMessage($chatId, "назад",$keyboard);
break;
}
function sendMessage($chat_id, $message, $replyMarkup) {
$s='';
if (isset($replyMarkup)) {
$s=json_encode($replyMarkup);
}
file_get_contents($GLOBALS['api'] . '/sendMessage?parse_mode=HTML&chat_id=' . $chat_id . '&disable_web_page_preview=true&text=' . urlencode($message) .'&reply_markup='.$s);
}

Answer 1

You are accessing the callback_query wrongly and additionally you need to take the chatId from the callback_query object.
$callback_query = $update['callback_query'];
$callback_data = callback_query["data"];
$chatId = callback_query["message"]["chat"]["id"];

Answer 2

change this $callback_query = $update['CallbackQuery']; to $callback_query = $update['callbackquery'];
you also need to add the following for callbackquery
$message_id = ['callback_query']['message']['message_id']; //callbackquery message id
$chat_id = $callback_query['message']['chat']['id']; // callbackquery chat id
i hope this helps