Storing Arrays in DB gives PHP Notice Undefined Offset 1 - php

Question

Getting an array from Android Client. Storing it in the DB gives a Notice: Undefined offset: 1 in C:\filepath\ on line 67
I am trying to achieve this in my DB:
User_Id | Book_Id
---------|---------
3 | 120
---------|---------
1 | 17
---------|---------
php file that collects the post from android client:
if(isset($_POST['watch'])){
$jsonwatch = $_POST['watch'];
$array = json_decode($jsonwatch, true);
$response["error"] =! ($db_watch->storeClass($array['attendees'], $array['lesson_iDs']));
}
php file that is called in the notice:
public function storeClass($attendees, $lesson_iDs) {
$stmt = $this->conn->prepare("INSERT INTO watch (date, user_id, lesson_id) VALUES(NOW(), ?, ?)");
$stmt->bind_param("ii", $attendees, $lesson_id);
foreach ($attendees as $index => $attendee) {
$lesson_id = $lesson_iDs[$index]; // Line 67
$result = $stmt->execute();
if(!$result){
echo '\n';
printf("Error for attendee %d in lesson %d : %s.\n", $attendee, $lesson_id, $stmt->error);
echo '\n';
echo '\n';
}
}
$stmt->close();
// result
return $result;
}
UPDATE!
var_dump($array):
C:\wamp64\www\ghanaweb\AddClass.php:19:
array (size=4)
'attendees' =>
array (size=2)
0 => string '5a6611e89e9e26.27646060' (length=23)
1 => string '5a4cfae69fd7b6.01373362' (length=23)
'id' => int 0
'lesson_iDs' =>
array (size=1)
0 => int 4
'lesson_id' => int 0
{"error":false}

Answer 1

Your problem is that you use the $ index as the ID in your case and it's only the number of the masive and nothing more
Try to use
$lesson_id = $lesson_iDs[$attendee['lesson_id']];

Answer 2

$lesson_iDs array has only one element and in the for loop you are trying to access a second element which is not existing