CodeIgniter, CI-Merchant and Paypal Sandbox - codeigniter

Question

I'm trying to make a little shopping cart with CodeIgniter and I found CI-Merchant to work with payment gateways with this guide http://ci-merchant.org/ but I don't really understand how to make it works with Paypal Sandbox.
$this->load->library('merchant');
$this->merchant->load('paypal_express');
$settings = array(
'username' => 'test#test.com',
'password' => '********',
'signature' => 'Test Store',
'test_mode' => true);
$this->merchant->initialize($settings);
$params = array(
'amount' => 12.00,
'currency' => 'CAD',
'return_url' => 'http://payment.test.com',
'cancel_url' => 'http://payment.test.com/cancel');
$response = $this->merchant->purchase($params);
$this->load->view('welcome_message');
I know that this code can't do much but it do nothing at all. Just load the view and nothing happens, I don't understand. So, my question is, do you know tutorials or just how to make CI Merchant works with Paypal Sandbox? Thanks for the help.

Answer 1

Ace's comment is spot on. There is nothing wrong with your code, but you need to inspect the $response object to see what the result (or error message) was.
$response = $this->merchant->purchase($params);
if ($response->success())
{
// mark order as complete
$gateway_reference = $response->reference();
}
else
{
$message = $response->message();
echo('Error processing payment: ' . $message);
exit;
}
You can also simply try this to inspect the object:
$response = $this->merchant->purchase($params);
echo '<pre>';
print_r($response);
exit;