The Castlegate IT WP Product Cart plugin extends the Product Catalogue plugin to include a shopping cart system. It supports all the features of the Product Catalogue plugin, including discounts and product variants. It does not provide a checkout system.

The plugin provides two widgets: Cart Contents and Add to Cart. The Add to Cart widget will only appear on single product pages. These plugins use $cart->render('contents') and $cart->render('add') respectively; see methods below for customization options.

The plugin provides a single function cgit_product_cart(), which retrieves the cart object. The object uses a singleton pattern, which means it can only have one instance.

$cart = cgit_product_cart();
$cart = Cgit\Products\Cart::getInstance(); // same as above

The Cgit\Products\Cart object provides various methods:

• $cart->render($view) returns the compiled output of a PHP file from the views directory within the plugin. There are two views: contents and add, which are used by the widgets to render content.

• $cart->update() this method is attached to the wp action and checks for submitted $_POST data, adding or removing products from the cart session accordingly.

• $cart-add($product, $quantity = false, $variant = false) adds one or more products to the cart. If no quantity is set, one product is added.

• $cart-add($product, $quantity = false, $variant = false) removes one or more products to the cart. If no quantity is set, all products are removed.

• $cart->contents() returns the cart contents from the stored session, or an empty array if the cart is empty.

• $cart::formatCurrency($number, $after = false, $sep = '') is the same as the formatCurrency method in the Cgit\ProductCatalogue class.

The cart contents are stored as an array in $_SESSION['cart']. A cart might something like:

$_SESSION = array(
    'cart' => array(
        array(
            'product' => 7, // product ID
            'quantity' => 2, // quantity
            'variant' => 3 // variant index from repeater field
        ),
        array(
            'product' => 4,
            'quantity' => 1,
            'variant' => false // this product does not have variants
        )
    )
);

The $cart->render() method provides filters called cgit_product_render_{name}, where {name} is contents or add. These filters allow you to edit or replace the default output. The filter allows a second argument, which includes the cart contents ($cart->contents()).