Beginning PHP 5.3 problem

RonInNewYork · April 29, 2011

I'm reading through this book which is actually not bad but, on page 286 there's a shopping_cart.php code (which I downloaded from the web site). The code that seems relevant to me is this:

<?php

$totalPrice = 0;

foreach ( $_SESSION["cart"] as $product) {

$totalPrice += $product->getPrice(); //<<<LINE 94

?>

The error I get is

Fatal error: Call to a member function getPrice() on a non-object in C:\usr\web\shopping_cart.php on line 94

Should $product be a cast to the Product object?

class Product {

private $productId;

private $productName;

private $price;

public function __construct( $productId, $productName, $price ) {

$this->productId = $productId;

$this->productName = $productName;

$this->price = $price;

}

public function getPrice() {

return $this->price;

}

//etc.

}

fugix · April 29, 2011

welcome to the site.. when you are inserting code, please use the code tags as this makes the code easily distinguishable.

wildteen88 · April 29, 2011

I'm reading through this book which is actually not bad but, on page 286 there's a shopping_cart.php code (which I downloaded from the web site). The code that seems relevant to me is this:

<?php

$totalPrice = 0;

foreach ( $_SESSION["cart"] as $product) {

$totalPrice += $product->getPrice(); //<<<LINE 94

?>

The error I get is

Fatal error: Call to a member function getPrice() on a non-object in C:\usr\web\shopping_cart.php on line 94

Should $product be a cast to the Product object?

Yes as long as you have initiated the object

$product = new Product;

RonInNewYork · April 29, 2011

But shouldn't the $product object already hold all the values? Product has only one constructor taking 3 parameters. Shouldn't the foreach code handle this? How would you write it?

I've tried casting $product to Product but that didn't work (Product)$product.

RON

wildteen88 · April 29, 2011

Where are you calling $product->getPrice()? Is it in the same file as when you initiated the product object (when you created the product). Or in a different page?

If its in a different page then variables you define in one page will not be passed on to the next. Variables die when the script finishes.

RonInNewYork · April 29, 2011

Here' s the entire code. It's just from a book as I'm learning PHP (after years in Java and C#/VB.NET):

<?php
session_start();

class Product {
  private $productId;
  private $productName;
  private $price;

  public function __construct( $productId, $productName, $price ) {
	$this->productId = $productId;
	$this->productName = $productName;
	$this->$price = $price;
  }

  public function getId() {
    return $this->productId;
  }

  public function getName() {
    return $this->productName;
  }

  public function getPrice() {
    return $this->price;
  }

}

$products = array(
  1 => new Product( 1, "SuperWidget", 19.99 ),
  2 => new Product( 2, "MegaWidget", 29.99 ),
  3 => new Product( 3, "WonderWidget", 39.99 )
);

if ( !isset( $_SESSION["cart"] ) ) $_SESSION["cart"] = array();

if ( isset( $_GET["action"] ) and $_GET["action"] == "addItem" ) {
  addItem();
} elseif ( isset( $_GET["action"] ) and $_GET["action"] == "removeItem" ) {
  removeItem();
} else {
  displayCart();
}

function addItem() {
  global $products;
  if ( isset( $_GET["productId"] ) and $_GET["productId"] >= 1 and $_GET["productId"] <= 3 ) {
    $productId = (int) $_GET["productId"];

    if ( !isset( $_SESSION["cart"][$productId] ) ) {
      $_SESSION["cart"][$productId] = $products[$productId];
    }
  }

  session_write_close();
  header( "Location: shopping_cart.php" );
}

function removeItem() {
  global $products;
  if ( isset( $_GET["productId"] ) and $_GET["productId"] >= 1 and $_GET["productId"] <= 3 ) {
    $productId = (int) $_GET["productId"];

    if ( isset( $_SESSION["cart"][$productId] ) ) {
      unset( $_SESSION["cart"][$productId] );
    }
  }

  session_write_close();
  header( "Location: shopping_cart.php" );
}

function displayCart() {
  global $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" xml:lang="en" lang="en">
  <head>
    <title>A shopping cart using sessions</title>
    <link rel="stylesheet" type="text/css" href="common.css" />
  </head>
  <body>

    <h1>Your shopping cart</h1>

    <dl>

<?php
$totalPrice = 0;

foreach ( $_SESSION["cart"] as $product) {
  
  $totalPrice += $product->getPrice(); //<<<THIS IS WHERE THE CODE ABENDS
?>
      <dt><?php echo $product->getName() ?></dt>
      <dd>$<?php echo number_format( $product->getPrice(), 2 ) ?>
      <a href="shopping_cart.php?action=removeItem&productId=<?php echo $product->getId() ?>">Remove</a></dd>
<?php } ?>
      <dt>Cart Total:</dt>
      <dd><strong>$<?php echo number_format( $totalPrice, 2 ) ?></strong></dd>
    </dl>

?>
    <h1>Product list</h1>

    <dl>
<?php foreach ( $products as $product ) { ?>
      <dt><?php echo $product->getName() ?></dt>
      <dd>$<?php echo number_format( $product->getPrice(), 2 ) ?>
      <a href="shopping_cart.php?action=addItem&productId=<?php echo $product->getId() ?>">Add Item</a></dd>
<?php } ?>
    </dl>

<?php
}

?>

  </body>
</html>

markjoe · April 29, 2011

I think objects need to be serialized to be stored in the $_SESSION array. Then of course unserialized when retrieved.

RonInNewYork · April 30, 2011

I'm not sure how to implement that. I can see the problem is getting at the Product objects in the $product array. When I put

if (isset($_SESSION["cart"] {

before the first foreach, then that code doesn't error out. HOWEVER, the second foreach does error

h1>Product List</h1>
<dl>
	<?php foreach ($products as $product) {?>
	<dt><?php echo $product->$getName() ?></dt>
	<dd>$<?php echo number_format($product->getPrice(),2) ?>
	<a href="shopping_cart.php?action=addItem&productId<=<?php echo $product->getId() ?>">Add Item</a></dd>
	<?php } ?>
</dl>

errors out with "Undefined variable: getName in...line" and "Method name must be a string."

Thanks for your help.

RON

wildteen88 · April 30, 2011

$product->$getName() should be $product->getName()

RonInNewYork · April 30, 2011

Thanks that was sloppy of me. But now I get:

Call to undefined method Product::getName()...

If it isn't one thing, it's another, right?

APOLOGIES: A couple of spelling and other typos. BUT, even when I fixed them the code seems incredibly broken. It will run with no errors, for instance $_SESSION["cart"] is always unset.

darkfreaks · April 30, 2011

have you tried using something like

http://us2.php.net/manual/en/function.session-set-save-handler.php

to store your sessions :confused:

RonInNewYork · April 30, 2011

Thanks. That is interesting as well, but I think this was an accretion of typos. It now works (more or less).

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Beginning PHP 5.3 problem

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