How to set a custom option of type "file" when adding a product to the cart in Magento?

Question

Using my own controller, I'm adding a product to the Magento cart. It has 3 custom options: 2 dropdown options (color and size) and a file option (design). The code adding the product to the cart is

// obtain the shopping cart
$cart = Mage::getSingleton('checkout/cart');

// load the product
$product = Mage::getModel('catalog/product')
    ->load($productId);

// do some magic to obtain the select ids for color and size ($selectedSize and $selectedColor)
// ...

// define the buy request params
$params = array(
    'product'       => $productId,
    'qty'           => $quantity,
    'options'       => array(
        $customOptionSize->getId()  => $selectedSize,
        $customOptionColor->getId() => $selectedColor,

        // set the file option, but how? 
    ),
);

// add this configuration to cart
$cart->addProduct($product, $paramObject);
$cart->save();

// set the cart as updated
Mage::getSingleton('checkout/session')->setCartWasUpdated(true);

My question is: How do I attach a certain file to the design option?

The file has already been transferred to the server side (actually via the request). I could, however, fake uploading if this would be required. But until now I have not found a single source of information on setting file custom options...

My best guess from a tour through the Magento sources, is that the buy request needs some additional data (not in the options, but in the params object), like: option_123_file => something, but what exactly is needed I did not figure out yet. This part of the Magento sources is rather, uhh, not so straight forward. Thanks for any help.

Answer 1

Ok finally figured this out. The params array needs special entry to tell the custom option with the key "options_xx_file_action" what to do with a file ('save_new' or 'save_old'). This would look like:

$params = array(
    'product'       => $productId,
    'qty'           => $quantity,
    'options'       => array(
        $customOptionSize->getId()  => $selectedSize,
        $customOptionColor->getId() => $selectedColor,
    ),
    'options_'.$customOptionDesign->getId().'_file_action'=>'save_new',
);

Obviously, you will need to add the file to the post request (via form or therelike). The name of the file should be "options_xx_file". For example, in my case my $_FILES looked like:

Array (
[options_108_file] => Array
    (
        [name] => i-like.png
        [type] => application/octet-stream
        [tmp_name] => C:\xampp\tmp\phpAAB8.tmp
        [error] => 0
        [size] => 6369
    )

)