Make the compare list work without filling the log_* tables?

Question

The Magento compare list feature only works, when the log_* tables are being filled. If they are not, the compare list is global, which means, whenever a customer adds to the list, every other customer can see that recently added item. I disabled (and cant enable) this feature by putting this in my local.xml:

<controller_action_predispatch> 
    <observers><log><type>disabled</type></log></observers> 
</controller_action_predispatch> 
<controller_action_postdispatch> 
    <observers><log><type>disabled</type></log></observers> 
</controller_action_postdispatch> 

Removing this makes the compare list work right away. The question is, is there a workaround for that? Is there a way to make the compare list work and not fill the log_* tables?

Thanks!

Answer 1

Sadly the compare items are tightly linked to the visitor information.

The table catalog_compare_item has a column for visitor_id which when you disable the observers mentioned in your question, is set to 0 and so all visitors can see these items.

When you add an item to the compare list the visitor is linked into that item.

Mage_Catalog_Model_Product_Compare_List::addProduct calls the protected function _addVisitorToItem which gets the visitor id set from the log/visitor and attaches this to the item, as well as the customer id when you are logged in.

protected function _addVisitorToItem($item)
{
    $item->addVisitorId(Mage::getSingleton('log/visitor')->getId());
    if (Mage::getSingleton('customer/session')->isLoggedIn()) {
        $item->addCustomerData(Mage::getSingleton('customer/session')->getCustomer());
    }

    return $this;
}

Without limiting the compare functionality to logged in customers only I cannot see a way around filling these log tables as Magento needs to know what visitor is actually requesting the items to be compared.

Answer 2

This is an old question, but for anybody who still stumbles across this wanted to point out a solution that Yireo developed. By overriding the getId function in Mage_Log_Model_Visitor with a fake user ID that is based on the session ID, functionality that depends on the log user ID continues to work:

// Return a bogus visitor-ID that is not logged at all, but used in various buggy Magento parts 
return abs(crc32(Mage::getModel('core/session')->getSessionId()));

See source here: https://github.com/yireo/Yireo_DisableLog/blob/master/source/app/code/community/Yireo/DisableLog/Model/Rewrite/Log/Visitor.php#L57

Note that you may be best off using their entire extension, as it provides additional related functionality to support disabling customer logging.