Variable giving me undefined index off 0 - php

Question

I'm currently building a social network. I got to the point where I need cookies and tokens (in the database) to make people logout and login in.
The problem is that for some reason one of my variables is not getting any data from the query I wrote...
Here's the code of the page:
Cookie_login.php
<?php declare(strict_types=1);
class Login
{
public static function isloggedIn(): ?int
{
if (isset($_COOKIE['SNID'])) {
$user = DB::query(
'SELECT user_id FROM tokens WHERE token=:token',
[':token' => sha1($_COOKIE['SNID'])]
);
if (empty($user) && isset($user[0]['user_id'])) {
$userid = $user[0]['user_id'];
}
if (isset($_COOKIE['SNID_'])) {
return $userid;
}
$cstrong = true;
$token = bin2hex(openssl_random_pseudo_bytes(64, $cstrong));
DB_update::query_update(
'INSERT INTO tokens VALUES (\'\',:token,:user_id)',
[':token' => sha1($token), ':user_id' => $userid]
);
DB_update::query_update('DELETE FROM tokens WHERE token=:token', [':token' => sha1($_COOKIE['SNID'])]);
setcookie('SNID', $token, time() + 60 * 60 * 24 * 7, '/', null, true, true);
return $userid;
}
return null;
}
}
and the DB.php
<?php
error_reporting(E_ALL);
ini_set('display_errors', 1);
class DB
{
private static function connect(): PDO
{
$pdo = new PDO('mysql:host=127.0.0.1;dbname=pap;charset=utf8', 'root', '');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
return $pdo;
}
public static function query($query, $params = [])
{
$statement = self::connect()->prepare($query);
$statement->execute($params);
return $statement->fetchALL();
}
}
class DB_update
{
private static function connect(): PDO
{
$pdo = new PDO('mysql:host=127.0.0.1;dbname=pap;charset=utf8', 'root', '');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
return $pdo;
}
public static function query_update($query_update, $paramss = [])
{
$statement = self::connect()->prepare($query_update);
$statement->execute($paramss);
return $statement->RowCount();
}
}
I used the fopen() and fwrite() to see what $userid is returning and it was returning 1... Already check the queries in SQL and they work just fine... So I don't know why the $userid variable is not saving the user_id from the table. I hope you guys can help me...
PS:DB_update is just a name to be different from DB_query

Answer 1

First, of all:
fwrite($fp, print_r($userid));
Function print_r has a second parameter, default sets to false but in your case, you have to explicity set to true:
fwrite($fp, print_r($userid, true));
Otherwise, you will always write to file 1 value.
And the second. It's good idea to use function fclose to close opened file pointer if it's no longer required.

Answer 2

This line generates your "undefined index off 0" error:
$userid = DB::query('SELECT user_id FROM tokens WHERE token=:token',
array(':token' =>sha1($_COOKIE['SNID'])))[0]['user_id'];
Specifically, the [0]['user_id'] bit that you've patched to the end of the query. You should only ever do that if you're sure the function called will always return an array with the necessary fields (not the case with DB queries!). When there is no match, your DB::query method probably returns NULL or false (and you can't have NULL[0] etc. much less NULL[0]['user_id'], thus the error).
You'll want to postpone the offset assignment, and first of all have a logic for situations where no match happens. First put the DB query result into a variable that you can evaluate as being the expected type of resource or not -- only then assign array offsets.
$user = DB::query('SELECT user_id FROM tokens WHERE token=:token',
array(':token' =>sha1($_COOKIE['SNID'])));
if (!empty($user) && isset($user[0]['user_id'])) {
$userid = $user[0]['user_id'];
}
else {
// whatever that you need to do here.
}
On your debugging trouble; your print_r logger is only logging 1 because:
print_r ( mixed $expression [, bool $return = FALSE ] ) : mixed
... "When the $return parameter is TRUE, this function will return a string.
Otherwise, the return value is TRUE."
If you want to both print and log into a file, then use an intermediate variable, along the lines of $pr = print_r($foo, true); echo $pr; fwrite($fp, $pr);. Hope that helps you get it sorted.

Answer 3

Ok, that's whole code with comments:
<?php
error_reporting(E_ALL);
ini_set('display_errors', 1);
class DB
{
private static function connect()
{
$pdo = new PDO('mysql:host=127.0.0.1;dbname=pap;charset=utf8','root','');
$pdo -> setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
return $pdo;
}
public static function query($query,$params=array())
{
$statement = self::connect() ->prepare($query);
$statement ->execute($params);
$data = $statement -> fetchALL();
return $data;
}
}
class DB_update
{
private static function connect()
{
$pdo = new PDO('mysql:host=127.0.0.1;dbname=pap;charset=utf8','root','');
$pdo -> setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
return $pdo;
}
public static function query_update($query_update,$paramss=array())
{
$statement = self::connect() ->prepare($query_update);
$statement ->execute($paramss);
$datas = $statement -> RowCount();
return $datas;
}
}
/**
* Table `tokens` schema:
* CREATE TABLE `tokens` (
* `token` varchar(255) NOT NULL,
* `user_id` int(11) NOT NULL,
* PRIMARY KEY (`token`)
* ) ENGINE=InnoDB DEFAULT CHARSET=utf8
*/
class Login
{
public static function isloggedIn()
{
if (isset($_COOKIE['SNID'])) {
$userid = DB::query('SELECT user_id FROM tokens WHERE token=:token',array(':token' =>sha1($_COOKIE['SNID'])))[0]['user_id'];
$fp = fopen('problem.txt', 'w');
fwrite($fp, print_r($userid, true));
fclose($fp);
// I don't understand, what is this ? There is no place in your code, to set that cookie in that named key
// It always be false
if (isset($_COOKIE['SNID_']))
{
return $userid;
}
else {
$cstrong = TRUE;
$token = bin2hex(openssl_random_pseudo_bytes(64, $cstrong));
DB_update::query_update('INSERT INTO tokens VALUES (:token,:user_id)',array(':token'=>sha1($token),':user_id'=>$userid));
DB_update::query_update('DELETE FROM tokens WHERE token=:token',array(':token'=>sha1($_COOKIE['SNID'])));
setcookie("SNID", $token, time() + 60 * 60 * 24 * 7, '/', NULL, TRUE, TRUE);
// I don't understand what is this below
setcookie("SNID:", '1', time() + 60 * 60 * 24 * 3, '/', NULL, TRUE, TRUE);
return $userid;
}
}
return false;
}
}
// Uncomment code below to log in
// $userIdToLogIn = 19; // You can change it to any other value
// $cstrong = true;
// $token = bin2hex(openssl_random_pseudo_bytes(64, $cstrong));
// DB_update::query_update('INSERT INTO tokens VALUES (:token, :user_id)', array(':token' => sha1($token), ':user_id' => $userIdToLogIn));
// setcookie("SNID", $token, time() + 60 * 60 * 24 * 7, '/', NULL, TRUE, TRUE);
// ------------------------------
// Uncomment code below to log out
// setcookie("SNID", time() - 3600);
// -------------------------------
// And check
$userId = Login::isloggedIn();
if($userId) {
printf(
"User with id: %s is logger in with token: %s",
$userId,
DB::query('SELECT token FROM tokens WHERE user_id = :user_id', array(':user_id' => $userId))[0]['token']
);
} else {
echo "User is not logger in!";
}
And now:
Uncomment lines for comment: Uncomment code below to log in for first request. Script log in you.
Comment it back for second and nexts requests to check how it works.