code to add to favourites fails silently - php

Question

I have a myList.php which should list all products added to my favourites and compute the total price of products.
here is the code:
<?php
include 'navigation.php'
?>
<div class='sectionContents'>
<?php
if (isset($_GET['action']) && $_GET['action'] == 'removed') {
echo "<div>" . $_GET['prod_name'] . " was removed from favourites.</div>";
}
if (isset($_SESSION['fav'])) {
$ids = "";
foreach($_SESSION['fav'] as $prod_id) {
$ids = $ids . $prod_id . ",";
}
// remove the last comma
$ids = rtrim($ids, ',');
include "db_connect.php";
$query = mysql_query("SELECT prod_id, prod_name, prod_price FROM tbl_product WHERE prod_id IN ('$ids')") or die(mysql_error());
$num = mysql_num_rows($query);
if ($num > 0) {
echo "<table border='0'>"; //start table
// our table heading
echo "<tr>";
echo "<th class='textAlignLeft'>Product Name</th>";
echo "<th>Price (MUR)</th>";
echo "<th>Action</th>";
echo "</tr>";
//also compute for total price
$totalPrice = 0;
while ($row = mysql_fetch_assoc($query)) {
extract($row);
$totalPrice += $prod_price;
//creating new table row per record
echo "<tr>";
echo "<td>{$prod_name}</td>";
echo "<td class='textAlignRight'>{$prod_price}</td>";
echo "<td class='textAlignCenter'>";
echo "<a href='remove_favourite.php?prod_id= {$prod_id}&prod_name={$prod_name}' class='customButton'>";
echo "<img src='shopping-cart-in-php/images/remove-from- cart.png' title='Remove from favourite' />";
echo "</a>";
echo "</td>";
echo "</tr>";
}
echo "<tr>";
echo "<th class='textAlignCenter'>Total Price</th>";
echo "<th class='textAlignRight'>{$totalPrice}</th>";
echo "<th></th>";
echo "</tr>";
echo "</table>";
echo "<br /><div><a href='#' class='customButton'>Home</a></div>";
} else {
echo "<div>No products found in your favourites. :(</div>";
}
} else {
echo "<div>No products in favourites yet.</div>";
}
?>
I use the add_to_fav.php below to add the products to my favourites:
<?php
session_start();
// get the product id
$prod_id = $_GET['prod_id'];
$prod_name = $_GET['prod_name'];
/*
* check if the 'fav' session array was created
* if it is NOT, create the 'fav' session array
*/
if (!isset($_SESSION['fav'])) {
$_SESSION['fav'] = array();
}
// check if the item is in the array, if it is, do not add
if (in_array($prod_id, $_SESSION['fav'])) {
// redirect to product list and tell the user it was added to favourites
header('Location: prod_list.php?action=exists&prod_id' . $prod_id . '&prod_name=' . $prod_name);
}
// else, add the item to the array
else {
array_push($_SESSION['fav'], $prod_id);
// redirect to product list and tell the user it was added to cart
header('Location: prod_list.php?action=add&prod_id' . $prod_id . '&prod_name=' . $prod_name);
}
?>
I am having "No products found in your favourites. :(" when i try to view the favourites
I have a counter like thing which shows the number of products in my favourites as well and it stays to 0.
Have I erred somewhere? Which mistake should I correct?

Answer 1

There are a few things that could be happening.
1) You are not starting the session before loading the favorites:
<div class='sectionContents'>
<?php
if(isset($_GET['action']) && $_GET['action']=='removed'){
echo "<div>" . $_GET['prod_name'] . " was removed from favourites.</div>";
}
session_start()
if(isset($_SESSION['fav'])){
2) Your SQL query in fact is not finding any product ids. You might want to debug the SQL and run it in phpmyadmin or your mysql interface to see if it in fact does return any results.
include "db_connect.php";
$query = "SELECT prod_id, prod_name, prod_price FROM tbl_product WHERE prod_id IN ('$ids')";
echo $query; // Print query for debugging
$result = mysql_query($query) or die(mysql_error());
$num = mysql_num_rows($result);
My guess is that this query is incorrect because of the single quotes around $ids
It should be:
$query = "SELECT prod_id, prod_name, prod_price FROM tbl_product WHERE prod_id IN ($ids)";
Also this can be simplified from:
$ids = "";
foreach($_SESSION['fav'] as $prod_id){
$ids = $ids . $prod_id . ",";
}
// remove the last comma
$ids = rtrim($ids, ',');
To:
$ids = implode(",", $_SESSION['fav']);