Object of class PDOStatement could not be converted to string (help) - php

Question

I've been trying for the last six hours to figure out what is wrong with my code. My page keeps outputting 'Catchable fatal error: Object of class PDOStatement could not be converted to string.' I don't know why! I looked at previous assignments, tried googling the type of error, and nothing has changed the output. I want to display my menu items by category id. Here's my code.
class Menu {
public $conn;
public function __construct() {
$db = new Database();
$this->conn = $db->conn;
}
public function __destruct() {
$this-> conn = null;
}
/* Get function */
public function __get($name) {
return $this->$name;
} // End get function
public function __set($name, $value){
$this->$name=$value;
}
public function menu_items($category_id = 0){
try {
$sql = "SELECT item_id, category, category_id, display_order, item_name, item_image, item_description, item_cost FROM menu_items WHERE category_id = $category_id";
$result = $this->conn->query($sql);
return $result;
}
catch (PDOException $e){
echo 'Error: ' . $e->getMessage();
exit();
}
}
}
UPDATE: Here is where everything is outputting. Could there be something wrong with this code instead?
include(ABSOLUTE_PATH . 'classes/menu.class.php');
// Create Menu object
$menu = new Menu();
$menu_categories = $menu->menu_categories();
include(ABSOLUTE_PATH . '_includes/header.inc.php');
?>
<hr />
<h2><?=$page?></h2>
<?
while($item = $menu_categories->fetch(PDO::FETCH_OBJ)) {
// Retrieve menu items
$menu_items = $menu->menu_items($menu_categories);
$item_count = $menu_items->rowCount();
if($item_count > 0) {
echo '<h3>' . $item->category . '</h3>';
?>
<table id="menu_items" class="listing">
<?
// Loop through menu records
while($item = $menu_items->fetch(PDO::FETCH_OBJ)) {
echo "\t<tr>\n";
echo "\t\t" . '<td class="item"><h4>' . $item->item_name . '</h4><p>' . $item->item_description . '</p></td>' . "\n";
echo "\t\t" . '<td class="price">$' . $item->item_cost . '</td>' . "\n";
echo "\t\t" . '<td class="image"><img src="' . URL_ROOT . '_assets/images/menu/' . $item->item_image . '" alt="' . $item->item_name . '" /></td>' . "\n";
echo "\t</tr>\n";
}
?>
</table>
<?
}}
?>
<hr />
<?
include(ABSOLUTE_PATH . '_includes/footer.inc.php');
?>

Answer 1

Aha
here is your problem:
while($item = $menu_categories->fetch(PDO::FETCH_OBJ)) {
// Retrieve menu items
$menu_items = $menu->menu_items($menu_categories); //<--Error
$item_count = $menu_items->rowCount();
You should call:
$menu_items = $menu->menu_items($item->id);
You are passing $menu_categories (a PDOStatement) into menu_items(), then trying to use it as a string directly in your query. That is where the error is actually occurring.
A good practice that would have made this error more apparent is to type check query parameters. So in menu_items():
public function menu_items($category_id = 0){
if(!is_numeric($category_id)) {
//Do something better here, but just for example
echo "Error";
return false;
}
try {
$sql = "SELECT item_id, category, category_id, display_order, item_name, item_image, item_description, item_cost FROM menu_items WHERE category_id = $category_id";
$result = $this->conn->query($sql);
return $result;
...