How can I modify an attribute before indexing from Magento?

If you have a use case that requires modifying an attribute before indexing from Magento to Algolia, you can implement a Magento backend observer by customizing the algolia_after_create_product_object event.

For example, if some of your product SKUs have a leading 0 in Magento (ie;0123456 ), you may wish to index both the original SKU and a modified version without the leading zero (ie: [0123456,123456]).

Here is an example customization to the events.xml file to modify the SKU indexing:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="algolia_after_create_product_object">
        <observer name="customalgolia_sku_modifier" instance="Algolia\CustomAlgolia\Observer\AlgoliaAfterCreateProductObject" />
    </event>
</config>

The object's data would get passed to the observer as custom_data:

public function execute(Observer $observer)
{
   /** @var \Magento\Framework\DataObject $data */
   $data = $observer->getData('custom_data');
   $sku = $data->getData('sku');

   // Massage skus however you like 
   // Keep in mind could be array or scalar 
   // (depending on whether simple vs configurable product etc.)

   $data->setData('sku', $sku);
}

For more details on this approach, please refer to this documentation. Please note that this customization is out-of-scope for our Support team.