Full Page Cache invalidation on cart (quote) change

Question

I\'m trying to add a block (button) to mini cart block: either to name=\"cart_sidebar\" or preferably name=\"topCart.extra_actions\" as it renders it\'

Answer 1

To anyone looking for a solution to the extra_actions PayPal button, there is a Magento patch fixing it (SUPEE-87_1.12.0.0_v1.patch).

Since it's a Magento patch, you can simply open the file "app/code/core/Enterprise/PageCache/Model/Container/Sidebar/Cart.php" and add these 2 functions after the _renderBlock function, which is exactly what the patch does:

    /**
 * Get Place Holder Block
 *
 * @return Mage_Core_Block_Abstract
 */
protected function _getPlaceHolderBlock()
{
    $block = parent::_getPlaceHolderBlock();
    $block->setChild('extra_actions', $this->_getExtraActionsChildBlock());
    return $block;
}

/**
 * Get child Block
 *
 * @return Mage_Core_Block_Abstract
 */
protected function _getExtraActionsChildBlock()
{
     $paypalShortcutBlock = Mage::app()->getLayout()->createBlock('paypal/express_shortcut');
     $paypalShortcutBlock->setTemplate('paypal/express/shortcut.phtml');
     $paypalShortcutBlock->setLayout(Mage::app()->getLayout());

     return $paypalShortcutBlock;
}

Understanding how this works can help for other similar problems.

Thanks Vinai by the way, very informative answer.