Integration Guide

Table Of Contents
Third-Party Shopping Carts – The Cart Upload Command
Implementing the Instant Update API With the Cart Upload Command
7
326 June 2012 PayPal Payments Standard Integration Guide
NOTE: One drawback with passing aggregate cart information is that buyers do not see the
individual items in their order on the PayPal payment pages.
The following HTML is identical to the example in “Passing Individual Item Details to
PayPal” on page 323, except here the example aggregates the individual item amounts and
item names into a single amount and a single item.
HTML for Aggregate Cart Detail to PayPal
<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_cart">
<input type="hidden" name="upload" value="1">
<input type="hidden" name="business" value="seller@designerfotos.com">
<input type="hidden" name="item_name_1" value="Aggregated items">
<input type="hidden" name="amount_1" value="3.00">
<input type="submit" value="PayPal">
</form>
Securing Your Shopping Cart
After you have customized you third-party shopping cart, protect against malicious users
tampering with the button code and submitting an incorrect charge by using one of the
methods described in Securing Your PayPal Payments Standard Buttons.
Implementing the Instant Update API With the Cart Upload
Command
The Instant Update API is a callback-style API that lets you update PayPal in real time with
shipping, insurance, and tax amounts when buyers change their shipping address on the
PayPal Review Your Payment page.
Read these topics to learn more about implementing the Instant Update API:
“About the Instant Update API and the Cart Upload Command” on page 326
“Best Practices for Implementing Instant Update” on page 329
“Other Considerations for Implementing Instant Update” on page 330
“Setting Up the Callback for Instant Update” on page 332
“Responding to the Callback for Instant Update” on page 333
About the Instant Update API and the Cart Upload Command
The Instant Update API is a server call to your callback server that instantly updates PayPal
pages and enhances the Express Checkout experience on the Review your information page.