Variable $connection is undefined. Impossible, what is happening there? - php

Question

Objective: I am in the process of creating a php login script.
Problem: I can't seem to be able to make my includes recognize the $connection variable even though it should be clearly defined in connection.php. As a result the value of my variable is nothing / NULL.
What I tried: I started with mysql but quickly noticed that it was the wrong approach and converted my code to mysqli. I checked for typos in all the $connection variables I have. I made sure the paths are correct. As a last resort I did a Google search but didn't find an answer or any useful hint to my scenario.
Problem: What is the reason for my variable not being defined?
Error Messages:
All those messages are related to this single variable no being defined for some reason:
Php Notice: Undefined variable: connection in C:\xampp\htdocs\aspie\Php\Core\Common.php on line 4
Php Warning: mysqli_real_escape_string() expects parameter 1 to be mysqli, null given in C:\xampp\htdocs\aspie\Php\Core\Common.php on line 4
Php Notice: Undefined variable: connection in C:\xampp\htdocs\aspie\Php\Core\Functions\Members.php on line 4
Php Warning: mysqli_query() expects parameter 1 to be mysqli, null given in C:\xampp\htdocs\aspie\Php\Core\Functions\Members.php on line 4
Php Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, null given in C:\xampp\htdocs\aspie\Php\Core\Functions\Members.php on line 5
// INITIALIZER
<?php
session_start();
// error_reporting(NULL);
include 'Connection.php';
include 'Common.php';
include 'Functions/Members.php';
?>
**// ERROR MESSAGES **
<?php
$connection_error = 'Our website is experiencing technical issues, please come back later.';
$wrong_login = 'Password and name are wrong.';
$member_registered = 'Access has been denied. You do not seem to be a registered user.';
?>
**// CONNECTION **
<?php
include 'Errors.php';
$connection = mysqli_connect('localhost', 'root', '', 'project') or exit ($connection_error);
?>
**// COMMON **
<?php
error_reporting();
function sanitize($connection, $data) {
global $connection;
global $data;
return mysqli_real_escape_string($connection, $data);
}
?>
**// MEMBERS **
<?php
function member_registered($connection, $name) {
$name = sanitize($connection, $name);
$query = mysqli_query($connection, "SELECT COUNT(`id`) FROM `members` WHERE `name` = '$name'");
return (mysqli_num_rows($query) == 1) ? true : false;
}
?>
**// LOGIN **
<?php
include 'Php/Core/Initializer.php';
if (member_registered($connection, 'ee')) {
echo "exists";
}
die("eee");
echo error_reporting();
if (empty($_POST) == false) {
$name = $_POST['name'];
$password = $_POST['name'];
if (empty($name) OR empty($password)) {
echo $wrong_login;
}
else if (member_registered($connection, $name) == false) {
echo $member_registered;
}
}
?>
UPDATE:
Now what I get: existseee;
The conditional doesnt work now even though its all set up right. Username doesnt exist so it should'nt echo "exists:
if (member_registered($connection, 'ee')) {
echo "exists";
}
die("eee");

Answer 1

In your case, the $connection variable inside your sanitize function isn't reachable.
Try to pass the $connection variable into your function, like this:
function sanitize($data, $connection) {
return mysqli_real_escape_string($connection, $data);
}
Read more about it here: http://php.net/manual/en/language.variables.scope.php
UPDATE
In **// MEMBERS ** you need to include the new parameter as well:
function member_registered($name, $connection) {
$name = sanitize($name, $connection);
$query = mysqli_query($connection, "SELECT COUNT(`id`) FROM `members` WHERE `name` = '$name'");
return (mysqli_num_rows($query) == 1) ? true : false;
}
and because of that your **// LOGIN ** should be updated as well:
include 'Php/Core/Initializer.php';
if (member_registered('ee', $connection)) {
echo "exists";
}
die("eee");
echo error_reporting();
if (empty($_POST) == false) {
$name = $_POST['name'];
$password = $_POST['name'];
if (empty($name) OR empty($password)) {
echo $wrong_login;
}
else if (member_registered($name, $connection) == false) {
echo $member_registered;
}
}
And make sure that the $connection variable is reachable everywhere where you need it.
UPDATE #2
Answer to your update:
it should be like this:
if (member_registered('ee', $connection)) {
echo "exists";
}
and not like this:
if (member_registered($connection, 'ee')) {
echo "exists";
}
the $connection is the second parameter.