PHP working in chrome but not in firefox - php

Question

My following piece of code works fine on chrome, however when I try to load it on firefox is says: 'Notice: Trying to get property of non-object in */loginTrueFunctions.php on line 23'
these are the "problem codes":
$firstName = $sqlObjectFirstName->firstName;
And:
$lastName = $sqlObjectLastName->lastName;
PHP code:
function getFullName($id, $mysqli_connect){
if(isset($_SESSION['login'])){
$queryFirstName = mysqli_query($mysqli_connect,"
SELECT firstName
FROM users
WHERE id = '$id'
LIMIT 1
");
$sqlObjectFirstName = mysqli_fetch_object($queryFirstName);
$firstName = $sqlObjectFirstName->firstName;
printf( ucfirst($firstName));
printf(' ');
$queryLastName = mysqli_query($mysqli_connect,"
SELECT lastName
FROM users
WHERE id = '$id'
LIMIT 1
");
$sqlObjectLastName = mysqli_fetch_object($queryLastName);
$lastName = $sqlObjectLastName->lastName;
printf( ucfirst($lastName));
}
}
Thanks in advance!
EDIT: if I call the result as an array, firefox gives no error nor a result, but then chrome gives this error: Cannot use object of type stdClass as array.
Then I change mysqli_fetch_object to mysqli_fetch_array, result: Chrome works fine, firefox doesn't give an error nor a result.

Answer 1

Probably your session (or cookie) contents are different between your browsers(for example, you are logged in with one, but not with the other). Do a
var_dump($_SESSION); var_dump($_COOKIE);
and see

Answer 2

Check the return value of mysqli_fetch_object($queryFirstName); before trying to access it. It's likely your query is not returning anything.
Another thing to mention is DO NOT EVER PASS USER DATA DIRECTLY INTO A QUERY as you are vulnerable to a sql injection attack. Just because you are using mysqli, doesn't make you immune. You have to use the features of mysqli such as prepared statements to avoid sql injection.

Answer 3

More likely then not the error appears on both browsers and there is just broken markup and they are fixing it in two different ways, one leaving your markup visible the other not. Without seeing code there is no way to know for sure.
PROTIP
You can select multiple fields from a database in a single call.
$res = mysqli_query($mysqli_connect,"
SELECT firstName, lastName
FROM users
WHERE id = '".(int)$id."'
LIMIT 1");
if (!$res) die("Error running query at ".__FILE__." : ".__LINE__);
$person = mysqli_fetch_object($res);
echo $person->firstName;
echo $person->lastName;

Answer 4

Post the code that is posting this data from the browser to the php script, it very well could be that the data you are submitting to the server is different because of the browsers.
also, where is the code that shows how your data is being called on the php side of things?