This PHP library is a basic implementation for the paypal mobile checkout NVP interface. For simplicities sake I am going to create a single controller for the checkout that will check to see if we have a token or not, and then process it accordingly.

We will require the Cana_Paypal libraries for this. Go ahead and grab them over on github:

https://github.com/arzynik/cana-paypal

First lets set up our object. You will need to create an api user/pass/sig on paypals site, or with the sandbox.

$paypal = new Cana_Paypal_Mobile;

$paypal->setApiVersion('3.0')
  ->setApiUrl('https://mobile.paypal.com/wc?t=')
  ->setApiUser('api_user')
  ->setApiPass('api_pass')
  ->setApiSignature('api_sig');

We next need to call the SetMobileCheckout method on the api. In this example we will switch between Set and Do checkout based on if there is a token. You can see how this all fits together by downloading the library and example at the bottom of the page.

if (empty($_GET['token'])) {
  // SetMobileCheckout
} else {
  // DoMobileCheckout
}

SetMobileCheckout is what we do first, then send the user off to paypal.

$response = $paypal->setAmt('5.00')
  ->setCurrencycode('USD')
  ->setDesc('Test Item')
  ->setReturnurl('http://'.$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'])
  ->setCancelurl('http://'.$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'])
  ->setCheckout($optionalParams ? optionalParams : null);

if ($paypal->getResponseStatus()) {
  // forward user off to paypal
  header('Location: '.$paypal->getApiUrl().urldecode($paypal->getToken()));
} else {
  // error
  print_r($response);
  exit;
}

When they come back, they will have a token. We take that token and authenticate it back to paypal to finish the transaction.

$response = $paypal->setToken($_GET['token'])
  ->doCheckoutPayment();

if ($paypal->getResponseStatus()) {
  // success!
  print_r($response);
  exit;
} else {
  // error
  print_r($response);
  exit;
}