PHP Functions and MySQL Connectivity - php

Question

I have a database.php file which stores the database connection info like this:
<?php
// Database connectivity stuff
$host = "localhost"; // Hostname for the database. Usually localhost
$username = "root"; // Username used to connect to the database
$password = "root"; // Password for the username used to connect to the database
$database = "blog"; // The database used
// Connect to the database using mysqli_connect
$connection = mysqli_connect($host, $username, $password, $database);
// Check the connection for errors
if (mysqli_connect_errno($connection)) {
// Stop the whole page from loading if errors occur
die("<br />Could not connect to the database. Please check the settings and try again.") . mysqli_connect_error() . mysqli_connect_errno();
}
?>
And also a functions.php file that has the following:
<?php
// Functions file for the system
function show_posts($user_id) {
$posts = array();
$sql = "SELECT body, stamp from posts where user_id = '$user_id' order by stamp desc";
$result = mysqli_query($connection, $sql);
}
function show_users() {
$users = array();
$sql = "SELECT id, username FROM users WHERE status = 'active' ORDER BY username";
$result = mysqli_query($connection, $sql);
while ($data = mysqli_fetch_array($result)) {
$users[$data->id] = $data->username;
}
return $users;
}
function following($user_id) {
$users = array();
$sql = "SELECT DISTINCT user_id FROM following WHERE follower_id = $user_id";
$result = mysqli_query($connection, $sql);
while ($data = mysqli_fetch_assoc($result)) {
array_push($users, $data->user_id);
}
return $users;
}
?>
Both files are inside an /includes folder. I now have a users.php files in which I want to display a list of users. Here's my code that tries to do that:
<?php
$users = show_users();
foreach ($users as $key => $value) {
echo $key . " " . $value;
}
?>
The problem I have is this:
Notice: Undefined variable: connection in
/Applications/MAMP/htdocs/blog/includes/functions.php on line 13
Warning: mysqli_query() expects parameter 1 to be mysqli, null given
in /Applications/MAMP/htdocs/blog/includes/functions.php on line 13
Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result,
null given in /Applications/MAMP/htdocs/blog/includes/functions.php on
line 15
The users.php file has require('includes/functions.php') and require('includes/database.php'). But somehow the values are not passed?. What am I doing wrong? Please help me out. I hope this makes sense. The problem with the undefined variable occurs for each function of the 3.

Answer 1

Either pass the $connection variable to your functions or make it global.
E.g:
function show_posts($connection, $user_id) {
$posts = array();
$sql = "SELECT body, stamp from posts where user_id = '$user_id' order by stamp desc";
$result = mysqli_query($connection, $sql);
}
OR
function show_posts($user_id) {
global $connection;
$posts = array();
$sql = "SELECT body, stamp from posts where user_id = '$user_id' order by stamp desc";
$result = mysqli_query($connection, $sql);
}

Answer 2

Try $GLOBALS['connection'] instead of $connection in your function. See more here