Since the post is no longer available online, I paste it here for reference, if anybody is interested, should be easy enough to update for Kirby 2:
Title: PayPal eCommerce store
When creating the new site for [kylebean.co.uk](http://kylebean.co.uk) I needed to create an online shop using Kirby.
# Explanation
This cart system builds a form for PayPal to receive and take payment. It uses `PHP sessions` to store products in an array called 'cart'. Each item in the array takes the UID for the product as it's key, and quantity as it's value.
# Plugin cart.php
My solution was to create a plugin called _cart_:
<?php
function get_cart() {
s::start();
$cart = s::get('cart', array());
return $cart;
}
function cart_logic($cart) {
if (isset($_REQUEST['action'])) {
$action = $_REQUEST['action'];
$id = $_REQUEST['id'];
switch ($action) {
case 'add':
if (isset($cart[$id])) {
$cart[$id]++;
} else {
$cart[$id] = 1;
}
break;
case 'update':
if (isset($_REQUEST['quantity'])) {
$quantity = intval($_REQUEST['quantity']);
if ($quantity < 1) {
unset($cart[$id]);
} else {
$cart[$id] = $quantity;
}
}
break;
case 'delete':
if (isset($cart[$id])) {
unset($cart[$id]);
}
break;
}
s::set('cart', $cart);
}
if (count($cart) == 0) {
go(url('shop'));
}
return $cart;
}
function cart_count($cart) {
$count = 0;
foreach ($cart as $id => $quantity) {
$count += $quantity;
}
return $count;
}
function cart_postage($total) {
$postage;
switch ($total) {
case ($total < 10):
$postage = 2.5;
break;
case ($total < 30):
$postage = 3.5;
break;
case ($total < 75):
$postage = 5.5;
break;
case ($total < 150):
$postage = 8;
break;
default:
$postage = 10;
}
return $postage;
}
You should update the cart_postage function to reflect your own shipping rates.
Content
The plugin expects the following structure in content:
- shop/shop.txt
- shop/cart/cart.txt
- shop/complete/complete.txt
- shop/XX-product/product.txt
Within shop/cart/cart.txt, you should write the email used on PayPal to receive payments:
Email: email@address.com
----
shop.php template
The shop template will list all products and allow people to add them to the cart.
<?php $cart = get_cart(); ?>
<?php $count = cart_count($cart); ?>
<!-- header here -->
<?php if ($count > 0): ?>
<p>You have <strong><?php echo $count ?> item<?php if ($count > 1) echo 's' ?></strong> in your cart.</p>
<p><a href="<?php echo url('shop/cart') ?>">View your Cart and Pay</a></p>
<?php endif ?>
<?php $products = $page->children()->visible() ?>
<?php foreach($products as $product): ?>
<article>
<h2><?php echo kirbytext($product->title(), false) ?></h2>
<?php echo kirbytext($product->text()) ?>
<form method="post" action="<?php echo url('shop/cart') ?>">
<input type="hidden" name="action" value="add">
<input type="hidden" name="id" value="<?php echo $product->uid() ?>">
<p>£<?php echo $product->price() ?> <button type="submit">Add to Cart</button></p>
</form>
</article>
<?php endforeach ?>
<?php if ($count > 0): ?>
<p class="align-right"><a class="button" href="<?php echo url('shop/cart') ?>" data-icon-after=" →">View your Cart and Pay</a></p>
<?php endif ?>
<!-- footer here -->
cart.php template
The cart template is used to show products in the cart, as well as to make changes to them.
<?php $cart = cart_logic(get_cart()) ?>
<?php $products = $page->siblings()->visible() ?>
<!-- header here -->
<form method="post" action="https://www.paypal.com/cgi-bin/webscr">
<input type="hidden" name="cmd" value="_cart">
<input type="hidden" name="upload" value="1">
<input type="hidden" name="business" value="<?php echo $page->email() ?>">
<input type="hidden" name="currency_code" value="GBP">
<table>
<thead>
<tr>
<th>Product</th>
<th>Quantity</th>
<th>Price</th>
</tr>
</thead>
<tbody>
<?php $i=0; $count = 0; $total = 0; ?>
<?php foreach ($cart as $id => $quantity): ?>
<?php if ($product = $products->findByUID($id)): ?>
<?php $product = $product->first() ?>
<?php $i++; ?>
<?php $count += $quantity ?>
<tr>
<th>
<input type="hidden" name="item_name_<?php echo $i ?>" value="<?php echo $product->title() ?>" />
<input type="hidden" name="amount_<?php echo $i ?>" value="<?php echo $product->price() ?>" />
<?php echo kirbytext($product->title(), false) ?>
</th>
<td><input data-id="<?php echo $product->uid() ?>" data-quantity="<?php echo $quantity ?>" pattern="[0-9]*" class="quantity" type="number" name="quantity_<?php echo $i ?>" min="1" value="<?php echo $quantity ?>"> <a href="<?php echo url('shop/cart') ?>?action=delete&id=<?php echo $product->uid() ?>">Remove</a></td>
<?php $prodtotal = floatval($product->price()->value)*$quantity ?>
<td>£<?php printf('%0.2f', $prodtotal) ?></td>
</tr>
<?php $total += $prodtotal ?>
<?php endif; ?>
<?php endforeach; ?>
</tbody>
<tfoot>
<tr>
<td colspan="2">Subtotal</td>
<td>£<?php printf('%0.2f', $total) ?></td>
</tr>
<tr>
<?php $postage = cart_postage($total) ?>
<td colspan="2" class="align-right">Postage</td>
<td>£<?php printf('%0.2f', $postage) ?></td>
</tr>
<tr>
<th colspan="2" class="align-right">Total</th>
<th>£<?php printf('%0.2f', $total+$postage) ?></th>
</tr>
</tfoot>
</table>
<p><button type="submit">Pay with PayPal</button></p>
<p>or <a href="<?php echo url('shop') ?>">continue shopping</a></p>
</form>
<!-- footer here -->
You can see this in action at kylebean.co.uk/shop.