Fatal error: Uncaught Error: Attempt to modify property "user_id" on null in

Question

I'm trying to figure out what's going on with my userspice 3.2 installation, and unfortunately their forum is closed and there doesn't seem to be anywhere else to get support. I followed the install instructions, got the green light that everything was set up correctly and upon returning to the index page I get:

Fatal error: Uncaught Error: Attempt to modify property "user_id" on null in /homepages/13/d904845752/htdocs/models/funcs.php:393 Stack trace: #0 /homepages/13/d904845752/htdocs/models/top-nav.php(69): isUserLoggedIn() #1 /homepages/13/d904845752/htdocs/index.php(21): require_once('/homepages/13/d...') #2 {main} thrown in /homepages/13/d904845752/htdocs/models/funcs.php on line 393

The code in question is:

function isUserLoggedIn()
{
    global $loggedInUser, $mysqli, $db_table_prefix;
    $stmt = $mysqli->prepare("SELECT
        id,
        password
        FROM " . $db_table_prefix . "users
        WHERE
        id = ?
        AND
        password = ?
        AND
        active = 1
        LIMIT 1");
    $stmt->bind_param("is", $loggedInUser->user_id, $loggedInUser->hash_pw);
    $stmt->execute();
    $stmt->store_result();
    $num_returns = $stmt->num_rows;
    $stmt->close();

    if ($loggedInUser == NULL) {
        return false;
    } else {
        if ($num_returns > 0) {
            return true;
        } else {
            destroySession("userCakeUser");
            return false;
        }
    }
}

The line it's mad about is:

$stmt->bind_param("is", $loggedInUser->user_id, $loggedInUser->hash_pw);

Unfortunately I'm not comfortable enough with OOP to understand what's going on here.

The error message says that `$loggedInUser` is null, which means that you can't use it as an object. Btw, why not check the session if the user is logged in instead of calling the database? — M. Eriksson, Mar 17 '22 at 21:42
You should probably have `if ($loggedInUser == NULL)` _before_ you're trying to use that variable as an object, so just put your query inside the `else` block and it should work. — M. Eriksson, Mar 17 '22 at 21:52
That seemed to work, weird that I seem to be the only one with his issue :S Thanks! — user3750017, Mar 17 '22 at 21:56
**Never store passwords in clear text or using MD5/SHA1!** Only store password hashes created using PHP's [`password_hash()`](https://php.net/manual/en/function.password-hash.php), which you can then verify using [`password_verify()`](https://php.net/manual/en/function.password-verify.php). Take a look at this post: [How to use password_hash](https://stackoverflow.com/q/30279321/1839439) and learn more about [bcrypt & password hashing in PHP](https://stackoverflow.com/a/6337021/1839439) — Dharman, Mar 17 '22 at 23:04

score 1 · Answer 1 · answered Mar 17 '22 at 23:04

The error is very clear. The variable $loggedInUser is NULL and it's not an object. You can't access a property of a non-object.

//                      VVV - NULL   VV - trying to access property
$stmt->bind_param("is", $loggedInUser->user_id, $loggedInUser->hash_pw);

To fix the problem, you should return early from the function when the variable is NULL.

function isUserLoggedIn()
{
    global $loggedInUser, $mysqli, $db_table_prefix;
    // Return early if null
    if ($loggedInUser === NULL) {
        return false;
    }

    $stmt = $mysqli->prepare("SELECT
        id,
        password
        FROM " . $db_table_prefix . "users
        WHERE
        id = ?
        AND
        password = ?
        AND
        active = 1
        LIMIT 1");
    $stmt->bind_param("is", $loggedInUser->user_id, $loggedInUser->hash_pw);
    $stmt->execute();
    $stmt->store_result();
    $num_returns = $stmt->num_rows;

    if ($num_returns > 0) {
        return true;
    }

    destroySession("userCakeUser");
    return false;
}

Fatal error: Uncaught Error: Attempt to modify property "user_id" on null in

1 Answers1