An example of how to use the PayPal NVP API in Lasso to perform an Express Checkout transaction.

Lasso PayPal Express Checkout

--- Include this at the top of every page, e.g., [library('config.inc')]. ---
[//lasso
	// include required tags
	// (these could also be loaded via LassoStartup)
	library('tags/dictionary.inc'); // http://tagswap.net/dictionary
	library('tags/paypal_nvpapi.inc');
	
	// create a new paypal object to work with
	var('pp') = paypal_nvpapi(
		-pwd='your-api-password',
		-user='your-api-username',
		-signature='your-api-signature',
		-test=true // use the sandbox server
	);
]

-- Process a user-submitted form with Express Checkout. ---
[//lasso
	// include standard configuration.
	library('config.inc');

	// call the SetExpressCheckout method
	// the [$response] variable will contain all of the 
	// parameters returned by PayPal, which you can 
	// access as member tags, e.g., [$response->foo]
	var('response') = $pp->SetExpressCheckout(
		-paymentaction='Authorization',
		-amt='19.95',
		-returnurl='your-return-url',
		-cancelurl='your-cancel-url'
	);
	
	// if the operation was successful...
	if($response->ack >> 'Success');
		// send the user to PayPal with the token you just got back
		redirect_url('https://www.sandbox.paypal.com/cgi-bin/webscr?cmd=_express-checkout&token=' + $response->token);
	else;
		'Could not continue due to an error.';
	/if;
]

-- User completes transaction and is redirected to your-return-url by PayPal. ---
[//lasso
	// include standard configuration.
	library('config.inc');

	// if the token param was passed to the page...
	if(action_param('token'));
		// set it to a variable
		var('token') = action_param('token');

		// call the GetExpressCheckoutDetails method
		var('response') = $pp->GetExpressCheckoutDetails( -token=$token);		
		
		// if the operation was successful...
		if($response->ack >> 'Success');
			// complete the transaction by calling the DoExpressCheckoutPayment method
			var('response') = $pp->DoExpressCheckoutPayment(
				-paymentaction='Authorization',
				-payerid=$response->payerID,
				-amt='19.95',
				-token=$token
			);

			if($response->ack >> 'Success');
				'Transaction successful!';
			else;
				'Transaction could not be completed due to an error.';
			/if;
		else;
			'Could not continue due to an error.';
		/if;
	else;
		'No token was passed to the page.';
	/if;
]