title: Integrating PayPal checkout with Codeigniter
body: <p>I currently working on integrating PayPal express checkout for digital goods using Codeigniter. I went through PayPal wizard which creates some HTML and JavaScript for the button and also few PHP files are created. However since the file are pure PHP and neither controllers or models I am not sure how to call them. HTML code has some form action:</p>
  
  <pre><code>&lt;form action='checkout.php' METHOD='POST'&gt;
  </code></pre>
  
  <p>Now where should I put this checkout PHP in models or view and can I call it via controller using something:</p>
  
  <pre><code>www.myweb.com/index.php/mypalpal_controller/paypal_function
  </code></pre>
  
  <p>And inside controller function should the call go like:</p>
  
  <pre><code>$this-&gt;user_model-&gt;checkout;
  </code></pre>
  
  <p>And would the checkout.php require further modification so that everything is inside the model class?
  Thanks.</p>