Add custom options pragmatically in products

Question

Say I have 1000 product in some category, Now I want to add custom options in it, How can it be done? Below in my custom option structure: Title Input Type Is Required Sort Order
size Dropdown No

sizes(S, M, L, XL) and so on

Answer 1

I have Tested @Adarsh code there is a bug in his code, So I have corrected and posted here:

1: changed is_required to is_require to solve required bug 2: added $optionInstance = $product->getOptionInstance()->unsetOptions();

to unset option or duplicate options will be added

   <? 
    $options = array(
                    'title' => 'Sizes',
                    'type' => 'drop_down',
                    'is_require' => 1,
                    'sort_order' => 0,
                    'values' => array(
                                    array(
                                        'title' => 'S',
                                        'price' => 0, 
                                        'price_type' => 'fixed',
                                        'sku' => '',
                                        'sort_order' => 1,
                                    ),
                                    array(
                                        'title' => 'M',
                                        'price' => 0, //your price
                                        'price_type' => 'percent',
                                        'sku' => 'test-product-sku',
                                        'sort_order' => 2,
                                    ),
                                    array(
                                        'title' => 'L',
                                        'price' => 0, //your price
                                        'price_type' => 'fixed',
                                        'sku' => '',
                                        'sort_order' => 3,
                                    ),
                                    array(
                                        'title' => 'XL',
                                        'price' => 0, //your price
                                        'price_type' => 'percent', //price type %
                                        'sku' => 'test-product-sku',
                                        'sort_order' => 4,
                                    )
                                )
                );


    $category_id = 302;//put your cat_id here
    $products = Mage::getModel('catalog/category')->load($category_id)
         ->getProductCollection();

    //loop to all products 
    foreach($products as $product){

$product = Mage::getModel('catalog/product')->load($product->getId());
$optionInstance = $product->getOptionInstance()->unsetOptions();

$product->setHasOptions(1);
if (isset($option['is_require']) && ($option['is_require'] == 1)) {
    $product->setRequiredOptions(1);
}
$optionInstance->addOption($options);
$optionInstance->setProduct($product);
$product->save();
    }

Answer 2

Try this code:

$options = array(
                'title' => 'Sizes',
                'type' => 'drop_down',
                'is_required' => 1,
                'sort_order' => 0,
                'values' => array(
                                array(
                                    'title' => 'S',
                                    'price' => 0, //your price
                                    'price_type' => 'fixed',
                                    'sku' => '',
                                    'sort_order' => 1,
                                ),
                                array(
                                    'title' => 'M',
                                    'price' => 0, //your price
                                    'price_type' => 'percent',
                                    'sku' => 'test-product-sku',
                                    'sort_order' => 2,
                                ),
                                array(
                                    'title' => 'L',
                                    'price' => 0, //your price
                                    'price_type' => 'fixed',
                                    'sku' => '',
                                    'sort_order' => 3,
                                ),
                                array(
                                    'title' => 'XL',
                                    'price' => 0, //your price
                                    'price_type' => 'percent', //price type %
                                    'sku' => 'test-product-sku',
                                    'sort_order' => 4,
                                )
                            )
            );


$category_id = your_category_id;
$products = Mage::getModel('catalog/category')->load($category_id)
     ->getProductCollection();

//loop to all products 
foreach($products as $prd){
    //$product = Mage::getModel('catalog/product')->load($prd->getId());
    //un-comment above line if below line doesn't work.

    $product = $prd;
    //comment above line if you have uncommented first line.

    $product->setProductOptions(array($options));
    $product->setCanSaveCustomOptions(true);
    $product->save();
}

This will set custom option to all products from specific category.

I haven't tested, but should work.