ILLEGAL & UNINITIALIZED string offset error [duplicate] - php

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"Notice: Undefined variable", "Notice: Undefined index", "Warning: Undefined array key", and "Notice: Undefined offset" using PHP
(29 answers)
Illegal string offset Warning PHP
(17 answers)
Closed 5 years ago.
I'm having trouble fixing my errors, the functions are working fine but i need to get rid of the errors
i have this following errors:
Warning: Illegal string offset 'userID' in C:\xampp\htdocs\checkout.php on line 15
Notice: Uninitialized string offset: 0 in C:\xampp\htdocs\checkout.php on line 15
Fatal error: Call to a member function fetch_assoc() on boolean in C:\xampp\htdocs\checkout.php on line 19
and heres my code:
CHECKOUT.PHP
<?php
// include database configuration file
include 'dbConfig.php';
include 'login.php';
// initializ shopping cart class
include 'Cart.php';
$cart = new Cart;
// redirect to home if cart is empty
if($cart->total_items() <= 0){
header("Location: index.php");
}
// set customer ID in session
$_SESSION['sessCustomerID'] = $sessData['userID']; //this is the ID for the logged in user
// get customer details by session customer ID
$query = $db->query("SELECT * FROM users WHERE id =".$_SESSION['sessCustomerID']);
$custRow = $query->fetch_assoc();
?>
LOGIN.PHP
<?php
session_start();
$sessData = !empty($_SESSION['sessData'])?$_SESSION['sessData']:'';
if(!empty($sessData['status']['msg'])){
$statusMsg = $sessData['status']['msg'];
$statusMsgType = $sessData['status']['type'];
unset($_SESSION['sessData']['status']);
}
?>
<div class="container">
<?php
if(!empty($sessData['userLoggedIn']) && !empty($sessData['userID'])){
include 'user.php';
$user = new User();
$conditions['where'] = array(
'id' => $sessData['userID'],
);
$conditions['return_type'] = 'single';
$userData = $user->getRows($conditions);
?>
DBCONFIG.PHP
<?php
//DB details
$dbHost = 'localhost';
$dbUsername = 'root';
$dbPassword = '';
$dbName = 'dbblair';
//Create connection and select DB
$db = new mysqli($dbHost, $dbUsername, $dbPassword, $dbName);
if ($db->connect_error) {
die("Unable to connect database: " . $db->connect_error);
}
?>

Answer 1

Line 15:
$_SESSION['sessCustomerID'] = $sessData['userID'];
Both error messages that refer to this line are very clear.
Warning: Illegal string offset 'userID' in C:\xampp\htdocs\checkout.php on line 15
$sessData is a string (this is what the error says and line #3 of login.php confirms this statement).
Individual string characters can be accessed using the square bracket syntax (similar to arrays) but the offset must be an integer. The offset is a string in your code, and this is what the error says (a string is not a legal value for the offset).
Notice: Uninitialized string offset: 0 in C:\xampp\htdocs\checkout.php on line 15
Because it expects an integer for the offset and you use a string instead, the interpreter converts the string to number and the result is 0. The message says that the offset 0 does not exist in the string (and this is correct, as $sessData is ''). As a result, $_SESSION['sessCustomerID'] is initialized with the empty string.
For PHP the two messages above are just a warning and a notice (i.e. the script can continue) but in fact they reveal a serious error in your code.
The string offset and the way you use $sessData in login.php tell that $sessData must always be an array. It's unexplainable why do you set it to an empty string. Line #3 of login.php should read:
$sessData = !empty($_SESSION['sessData']) ? $_SESSION['sessData'] : array();
Lines 18 and 19:
$query = $db->query("SELECT * FROM users WHERE id =".$_SESSION['sessCustomerID']);
$custRow = $query->fetch_assoc();
The error:
Fatal error: Call to a member function fetch_assoc() on boolean in C:\xampp\htdocs\checkout.php on line 19
Information about this error was asked and answered dozen of times on [so]. I won't repeat the answer here.
mysqli::query() returns
FALSE when the query has syntax errors or refers to object that does not exist in the database. In this case, the query ends with WHERE id= because $_SESSION['sessCustomerID'] is empty, as explained above.
But $_SESSION['sessCustomerID'] is still empty on the first page load, even if you fix the initialization of $sessData. Apart from using prepared statements (see the linked answer for details), you should not issue a query to the database if you know in advance you won't get any result (this happens when $_SESSION['sessCustomerID'] is empty).