Set Sorting Direction / Order for a specifi Category when FPC is enabled

As we know, sorting option of a category is persistent on different categories. Which means if you select sorting option as "Price" for a Category 1 and go to Category 2 sorting option will be selected as "Price" though default sorting is selected as "Best Value".


Scenario:
Suppose there is a category as "New" and default category for "New" is "Product New from Date (news_from_date)" attribute.

When ever customer comes to New category, default sorting option should be selected as "New" (news_from_date), which means Sorting persistence should not affect New Category.

Step (1):
- Go to BO => Catalog => Categories => Manage Categories => Select Category "Niw"
- Under Display Settings Tab
---- Default Product Listing Sort By = "Set Product as New from Date"
- Under Custom Design Tab
---- Custom Layout Update:
 <reference name="product_list_toolbar">
  <action method="setDefaultDirection"><string>desc</string></action>
</reference>

Step (2):
app/code/local/ISM/New/etc/config.xml

<config>

<frontend>
    <events>
        <core_block_abstract_to_html_before>
            <observers>
                <ism_sorting_new_category>
                    <class>ism_new/observer</class>
                    <method>unsetSortingNewCategory</method>
                </ism_sorting_new_category>
            </observers>
        </core_block_abstract_to_html_before>
        <controller_action_postdispatch_catalog_category_view>
            <observers>
                <ism_disable_cache_for_new_category>
                    <class>ism_new/observer</class>
                    <method>disableCacheForNewCategory</method>
                </ism_disable_cache_for_new_category>
            </observers>
        </controller_action_postdispatch_catalog_category_view>
    </events>
</frontend>

</config>

Step (3):
app/code/local/ISM/New/Model/Observer.php

/** * Disable parameter memorizing and unset sorting order & category for category "Nieuwe"(New) * @param Varien_Event_Observer $observer * @return $this */

public function unsetSortingNewCategory(Varien_Event_Observer $observer)
{
    $block = $observer->getBlock();
    if ($block instanceof Mage_Catalog_Block_Product_List) {
        $category = Mage::registry('current_category');
        if ($category && $category->getDefaultSortBy() == 'news_from_date') {
            $sortingOrder = Mage::app()->getRequest()->getParam('order', false);
            $sortingDirection = Mage::app()->getRequest()->getParam('dir', false);

            if (!$sortingOrder && !$sortingDirection) {
                Mage::getSingleton('catalog/session')->unsSortOrder();
                Mage::getSingleton('catalog/session')->unsSortDirection();
            }
        }
    }

    return $this;
}

/** * Disable Cache for New (Nieuwe) category * @param Varien_Event_Observer $observer * @return $this */

public function disableCacheForNewCategory(Varien_Event_Observer $observer)
{
    $category = Mage::registry('current_category');

    if ($category && $category->getDefaultSortBy() == 'news_from_date') {
        $request = $observer->getEvent()->getControllerAction()->getRequest();
        $request->setParam('no_cache', true);
    }

    return $this;
}