How to fix Warning: Invalid argument supplied for foreach() - php

Question

I'm setting an edit user page on my local machine using PHP. There is this error
Warning: Invalid argument supplied for foreach() on line 79(<?php foreach ($user as $key => $value) : ?>)
I have tried to solve it, but in vain. I'm kinda new to PHP. Maybe there is something that I am missing or not seeing. Kindly assist and correct me if need be. Below is my code from the update.php page.
<?php
ini_set('display_errors', '1');
ini_set('display_startup_errors', '1');
error_reporting(E_ALL);
include_once 'core/init.php';
require 'common.php'; //Escapes HTML for output
if (isset($_POST['submit'])) {
try{
$this->dbh = new PDO($dsn, $this->user, $this->pass, $options);
$user = [
"id" => $_POST['id'],
"username" => $_POST['username'],
"email" => $_POST['email'],
"join_date" => $_POST['join_date']
];
$DB->query ('UPDATE users
SET id = :id,
username = :username,
email = :email,
join_date = :join_date
WHERE id = :id');
$DB->execute();
}
catch(PDOException $e){
echo $this->error = $e->getMessage();
}
}
if (isset($_GET['id'])) {
try{
$this->dbh = new PDO($dsn, $this->user, $this->pass, $options);
$id = $_GET['id'];
$DB->query('SELECT * FROM users WHERE id = :id');
$DB->bind(':id', $id);
$DB->execute();
$result=$DB->resultset();
// Catch any errors
}
catch(PDOException $e){
echo $this->error = $e->getMessage();
}
}
?>
<?php include "templates/header.php"; ?>
<?php if (isset($_POST['submit']) && $DB) : ?>
<blockquote><?php echo escape($_POST['username']); ?> successfully updated.</blockquote>
<?php endif; ?>
<h2>Edit a user</h2>
<form method="post">
<?php foreach ($user as $key => $value) : ?>
<label for="<?php echo $key; ?>"><?php echo ucfirst($key); ?></label>
<input type="text" name="<?php echo $key; ?>" id="<?php echo $key; ?>" value="<?php echo escape($value); ?>" <?php echo ($key === 'id' ? 'readonly' : null); ?> >
<?php endforeach; ?>
<input type="submit" name="submit" value="Submit">
</form>
Back to home
<?php include "templates/footer.php"; ?>

Answer 1

You are not setting any value for initial loading for variable $user, so it is undefined in foreach, so either use
$user = [];
if (isset($_POST['submit'])) {
try{
Or check and set value for $user
<?php foreach ($user ?? [] as $key => $value) : ?>