ProductUpdateTask.php

<?php

	class ProductUpdateTask extends BuildTask{

		protected $title = 'Product Update Task';
		protected $description = 'Update Products to the new class';

		protected $enabled = true;

		function run($request){
            $updateProduct = function($self){
                $product = ProductPage::get()->byID($self->ID);
                $product->ClassName = 'NestProduct';
                $product->write();
                $product->doPublish();
                echo "<p>{$self->Title} updated to {$self->ClassName}</p>";
            };

			$products = ProductPage::get();
            $products->each($updateProduct);

		}

	}