René Dahl Hansen René Dahl Hansen - 2 months ago 18
PHP Question

PHP, Error in Shopping Cart Program

I am trying to create a Shopping Cart in PHP. It worked fine. But then I removed all items from the Shopping Cart and it failed. I think it has something with the session, but I not complete sure.
I am getting this error:

Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in C:\Apache24\htdocs\phpshop\index.php on line 85
Call Stack
# Time Memory Function Location
1 0.0002 244096 {main}( ) ...\index.php:0
2 0.0017 255352 mysqli_fetch_array ( )


I used this Shopping cart tutorial to build this program.

cart.php code:

<?php



if(isset($_POST['submit']))
{

foreach($_POST['quantity'] as $key => $val)
{
if($val==0)
{
unset($_SESSION['cart'][$key]);


}
else
{
$_SESSION['cart'][$key]['quantity']=$val;
}
}

}

?>

<h1>View cart</h1>
<a href="index.php?page=products">Go back to products page</a>
<form method="post" action="index.php?page=cart">

<table>

<tr>
<th>Name</th>
<th>Quantity</th>
<th>Price</th>
<th>Items Price</th>
</tr>

<?php

$sql="SELECT * FROM products WHERE id_product IN (";

foreach($_SESSION['cart'] as $id => $value)
{
$sql.=$id.",";
}




$sql=substr($sql, 0, -1).") ORDER BY name ASC";


line 85 about here ---> $query = mysqli_query($con,$sql);

$totalprice=0;

$numrows = mysqli_num_rows($query);

if($numrows == 0)
{

header("Location: index.php");

}

while($row=mysqli_fetch_array($query))
{
$subtotal=$_SESSION['cart'][$row['id_product']]['quantity']*$row['price'];
$totalprice+=$subtotal;
?>
<tr>
<td><?php echo $row['name'] ?></td>
<td><input type="text" name="quantity[<?php echo $row['id_product'] ?>]" size="5" value="<?php echo $_SESSION['cart'][$row['id_product']]['quantity'] ?>" /></td>
<td><?php echo $row['price'] ?>$</td>
<td><?php echo $_SESSION['cart'][$row['id_product']]['quantity']*$row['price'] ?>$</td>
</tr>
<?php

}
?>
<tr>
<td colspan="4">Total Price: <?php echo $totalprice ?></td>
</tr>

</table>
<br />
<button type="submit" name="submit">Update Cart</button>
</form>
<br />
<p>To remove an item, set it's quantity to 0. </p>


index.php

<?php




session_start();









require("includes/connection.php");
if(isset($_GET['page'])){

$pages=array("products", "cart");

if(in_array($_GET['page'], $pages)) {

$_page=$_GET['page'];

}else{

$_page="products";

}

}
else{

$_page="products";

}
?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="stylesheet" href="css/reset.css" />
<link rel="stylesheet" href="css/style.css" />

<title>Shopping cart</title>

</head>

<body>

<div id="container">

<div id="main">

<?php require($_page.".php"); ?>

</div><!--end main-->

<div id="sidebar">

<h1>Cart</h1>
<?php

if(isset($_SESSION['cart'])){

$sql="SELECT * FROM products WHERE id_product IN (";

foreach($_SESSION['cart'] as $id => $value)
{
$sql.=$id.",";
}







$sql=substr($sql, 0, -1).") ORDER BY name ASC";
$query = mysqli_query($con,$sql);
while($row=mysqli_fetch_array($query))
{

?>
<p><?php echo $row['name'] ?> x <?php echo $_SESSION['cart'][$row['id_product']]['quantity'] ?></p>
<?php

}
?>
<hr />
<a href="index.php?page=cart">Go to cart</a>
<?php

}
else
{

echo "<p>Your Cart is empty. Please add some products.</p>";

}

?>

</div><!--end sidebar-->

</div><!--end container-->

</body>
</html>


products.php

<?php



if(isset($_GET['action']) && $_GET['action']=="add")
{

$id=intval($_GET['id']);

if(isset($_SESSION['cart'][$id])){

$_SESSION['cart'][$id]['quantity']++;

}

else
{

$sql_s="SELECT * FROM products WHERE id_product={$id}";

$query_s=mysqli_query($con,$sql_s);

if(mysqli_num_rows($query_s)!=0)
{
$row_s=mysqli_fetch_array($query_s);

$_SESSION['cart'][$row_s['id_product']]=array
(
"quantity" => 1,
"price" => $row_s['price']
);


}
else
{

$message="This product id it's invalid!";

}

}

}

?>

<h1>Product List</h1>

<?php
if(isset($message)){
echo "<h2>$message</h2>";
}
?>
<table>
<?php

$sql = "SELECT * FROM products ORDER BY name ASC";
$query = mysqli_query($con,$sql);

while ($row=mysqli_fetch_array($query)) {

?>
<tr>
<td><?php echo $row['name'] ?></td>
<td><?php echo $row['description'] ?></td>
<td><?php echo $row['price'] ?>$</td>
<td><a href="index.php?page=products&action=add&id=<?php echo $row['id_product'] ?>">Add to cart</a></td>
</tr>
<?php

}

?>
</table>

Answer Source

Your assignment of

$query = mysqli_query($con,$sql);

is failing and returning a boolean value of FALSE. This is because $con is not being set properly.

http://php.net/manual/en/mysqli.query.php

so, you are passing FALSE into mysqli_fetch_array as the $query

while($row=mysqli_fetch_array($query))

This is causing the error you reported

Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in C:\Apache24\htdocs\phpshop\index.php on line 85