Holepunching of header in magento store

Question

I have implemented hole-punching of header in Magento, and even though I have got it working on a per-customer basis, I need the ability to take this one level deeper by making it work on diff cart items counts too.

Here is my code.

    class AD_PageCache_Model_Container_Header extends Enterprise_PageCache_Model_Container_Abstract {

    protected function _getIdentifier() {
        return $this->_getCookieValue(Enterprise_PageCache_Model_Cookie::COOKIE_CUSTOMER, '');
    }

    // public function getCacheKeyInfo() {
    //  $info = parent::getCacheKeyInfo();
    //  die('boo');
    //  $info['cart_count'] = Mage::helper( 'checkout/cart' )->getCart()->getItemsCount();

    //  return $info;
    // }

    protected function _getCacheId() {
        //return 'CONTAINER_HEADER_' . md5($this->_placeholder->getAttribute('cache_id') . $this->_placeholder->getAttribute('cart_count') ) . '_' . $this->_getIdentifier();
        return 'CONTAINER_HEADER_' . md5( $this->_placeholder->getAttribute('cache_id') . $this->_getIdentifier() );
    }

    protected function _renderBlock() {
        $blockClass = $this->_placeholder->getAttribute('block');
        $template = $this->_placeholder->getAttribute('template');

        $block = new $blockClass;
        $block->setTemplate($template);
        return $block->toHtml();
    }

}

My understanding from what I have been reading from hole-punching threads on Magento is that the Mage app is not initialized when the FPC cache is serving the request, so basically, the method of adding a placeholder attribute can't work, since

Mage::helper( 'checkout/cart' )->getCart()->getItemsCount();

won't work, right?

And even though how is that it should be, but it didn't seem to run at all like I placed a die() call in there but nothing happened.

So what I am missing? And how can I retrieve the cart items count so that it can be used to build the cache ID?

Progress: I found

Enterprise_PageCache_Model_Cookie::COOKIE_CART

but this changes only once upon cart updation. After that, it stays the same. This is weird, this feels like the solution but its behavior says otherwise.

I couldn't find cart items count in session either. So the only way I currently see to do this would be to save the cart quantity in session whenever it updates and then uses that in _getIdentifier().

I found that observers are inconsistent with the cart. In addition, updation the events are dispatched but for removal, it doesn't. So I guess I can add my observer to price updation of the quote somehow if that is consistent in having observers?

Also, I did read Full Page Cache invalidation on the cart (quote) change but it handles using

Enterprise_PageCache_Model_Cookie::COOKIE_CART

which doesn't work well in my case, although I think the problem lies inside it. What/How? I am not sure.

Also the current version of EE we have running doesn't even have Advanced folder under Model/Container. I am using EE 1.10.1.1

Any suggestions?

Answer 1

Using Enterprise_PageCache_Model_Cookie::COOKIE_CART is the right way to go, but you may need to do some changes.

Enterprise_PageCache_Model_Observer::registerQuoteChange is called on every quote save (item number change included) and it is also called in the context on Mage::app() so you can access all session data. Overwrite this observer and add more data in $this->_getCookie()->setObscure so the value changes whenever you need to.