Allows to override a value in the Category column of a products CSV file before the data is imported.
The event handler should accept a single parameter - the Category column value. The handler should
either return the updated column value or FALSE if the value should not be updated.
public function subscribeEvents()
{
Backend::$events->addEvent('shop:onOverrideProductCategoryCsvImportData', $this, 'override_csv_product_category');
}
public function override_csv_product_category($value)
{
return str_replace('^', '|', $value);
}