PHP Session variable is empty when it's not empty

Question

I've got a login system set up, and there are no problems with staying logged in. Both userid and username are stored as session variables (and stored in a table in the database), and I can access them for use within the html on the pages themselves just fine.

I have a form with several multiple choice questions. Any answers I put in the form are stored in the database correctly, no problems there. But when I try to put the username or id into the table, it doesn't work.

The username is displayed on survey.php (the page with the form on it) in the html, like so:

<h2><?php
    echo $_SESSION['userName'];
?></h2>

Before I submit the form, the username is displayed correctly. After submitting the form, the same page reloads and the username is still displayed correctly. I'm not being logged out. $_SESSION['userName'] is not being reset and it's not empty.

The code below works perfectly as is, but if I replace

$locationMC = $_POST['locationMC'];

with

$locationMC = $_SESSION['userName']; # (the commented out line in the code below)

it redirects me to /survey.php?error=emptyfields, so $locationMC isn't being set when I try to use the session variable.

The users table and testingtable are in the same database. UserID is set as the primary key, but userName isn't indexed.

Something tells me I'm missing something super basic here -- I'm really new to this -- but after hours of searching on google, I can't figure out what the problem is. Thanks for any help!

<?php
if (isset($_POST['submit'])) {
    
    require 'dbh.inc.php';
    
    $locationMC = $_POST['locationMC'];
    # $locationMC = $_SESSION['userName'];
    $genderMC = $_POST['genderMC'];
    $religionMC = $_POST['religionMC'];
    

    if (empty($locationMC)) {
        header("Location: ../survey.php?error=emptyfields");
        exit();
    }
    else {
        $sql = "INSERT INTO testingtable (locationMC, genderMC, religionMC) VALUES (?, ?, ?)";
        $stmt = mysqli_stmt_init($conn);
        if (!mysqli_stmt_prepare($stmt, $sql)) {
            header("Location: ../survey.php?error=sqlerror");
            exit();
        } else {
            mysqli_stmt_bind_param($stmt, "sss", $locationMC, $genderMC, $religionMC);
            mysqli_stmt_execute($stmt);
            header("Location: ../survey.php");
            exit();
        }
    }
    mysqli_stmt_close($stmt);
    mysqli_close($conn);
}
else {
    header("Location: ../survey.php");
    exit();
}

Below is dbh.inc.php. It's the same file that's used when signing up and logging in.

<?php
$servername = "localhost";
$dBUsername = "root";
$dBPassword = "";
$dBName = "testingdb";

$conn = mysqli_connect($servername, $dBUsername, $dBPassword, $dBName);

if (!$conn) {
    die("Connection failed: ".mysqli_connect_error());
}

How do you know it is not empty. Have you tried print_r($_SESSION); — smartdroid
– smartdroid, Commented Jul 15, 2020 at 4:13
@smartdroid on the page itself, I did print_r($_SESSION); before and after running the above script, and it always has the correct information (Array ( [userId] => 42 [userName] => bob33 )). Inside the script, I did $genderMC = print_r($_SESSION); and all it added to the database was 1. — spunkystella
– spunkystella, Commented Jul 15, 2020 at 5:15
You should not be adding session_start(); if session is already started, or you will be resetting your session on each reload, which will cause the session username to be nulled on reload — Ron
– Ron, Commented Jul 16, 2020 at 1:18

Ahmed Hekal · Accepted Answer · 2020-07-16 01:20:26Z

1

you need to start request session to read its content

add this code in you top header

if(!isset($_SESSION)) session_start();

answered Jul 16, 2020 at 1:20

Ahmed Hekal

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5 Comments

spunkystella Over a year ago

I replaced session_start(); with what you posted, and it didn't change anything. It's still not working, but thanks!

Ahmed Hekal Over a year ago

hello dear , add this code in top of you page , and try to output al session info in this mode echo '<pre>'; print_r($_SESSION); echo '<pre>';

spunkystella Over a year ago

It gives me Array ( [userId] => 42 [userName] => bob33 ) every time I load the page, which is what it should show.

spunkystella Over a year ago

Your solution has partially fixed it. I can do $locationMC = print_r($_SESSION, true); and it'll put Array ( [userId] => 42 [userName] => bob33 ) into the database. But if I do $locationMC = $_SESSION['userName']; it still says that the value is empty (redirecting me to error=emptyfields). So big thanks for your help!

spunkystella Over a year ago

Problem solved. Had a typo. Everything's working now, so your solution fixed it. Thank you!

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