Redirecting Associated Products to Grouped Product

Question

I have been expanding my catalog and have run into a few suppliers that are carrying the exact same products. The only difference is the price and stock levels.

To avoid duplicate products on my website (and search engine penalties), I've created a Grouped Product with the name of the product and have added the 2 identical products from the 2 different suppliers and have set them to "Not visible individually"

The problem I now face is that by setting the Associated Products to "Not visible individually" is that the link becomes dead.

What I would like to do is to automatically create a redirect to the Grouped Product for all Associated Products

How do you create redirects of Associated Products to the Grouped Product ?

Answer 1

The idea is this. When viewing a product page check to see if the product belongs to a grouped product. If so, redirect to the main product page.
There is a catch. A simple product can be part of more than one grouped product. In this case the simplest approach is to redirect to the first one found.

Here is some code you can use.
Create an extension. Let's call it StackExchange_Grouped.

app/etc/modules/StackExchange_Grouped.xml - the declaration file

<?xml version="1.0"?>
<config>
    <modules>
        <StackExchange_Grouped>
            <codePool>local</codePool>
            <active>true</active>
            <depends>
                <Mage_Catalog />
            </depends>
        </StackExchange_Grouped>
    </modules>
</config>

app/code/local/StackExchange/Grouped/etc/config.xml - the module configuration file where you declare an observer for the product view page

<?xml version="1.0"?>
<config>
    <modules>
        <StackExchange_Grouped>
            <version>1.0.0</version>
        </StackExchange_Grouped>
    </modules>
    <global>
        <models>
            <stackexchange_grouped>
                <class>StackExchange_Grouped_Model</class>
            </stackexchange_grouped>
        </models>
    </global>
    <frontend>
        <events>
            <controller_action_predispatch_catalog_product_view>
                <observers>
                    <stackexchange_grouped>
                        <class>stackexchange_grouped/observer</class>
                        <method>redirectToParent</method>
                    </stackexchange_grouped>
                </observers>
            </controller_action_predispatch_catalog_product_view>
        </events>
    </frontend>
</config>

app/code/local/StackExchange/Grouped/Model/Observer.php - the observer that should redirect to the grouped product page.

<?php
class StackExchange_Grouped_Model_Observer
{
    public function redirectToParent($observer)
    {
        $id = Mage::app()->getRequest()->getParam('id');
        $groupedParentIds = Mage::getResourceSingleton('catalog/product_link')
            ->getParentIdsByChild($id,
                Mage_Catalog_Model_Product_Link::LINK_TYPE_GROUPED);
        if (isset($groupedParentIds[0])) {
            $mainProduct = Mage::getModel('catalog/product')
                ->setStoreId(Mage::app()->getStore()->getId())->load($groupedParentIds[0]);
            Mage::app()->getResponse()->setRedirect($mainProduct->getProductUrl(), 301);
            Mage::app()->getResponse()->sendResponse();
            exit;
        }
        return $this;
    }
}

Clear the cache and give it a go.