<?php
class ProductPage extends Page {
	private static $many_many = array(
		'RelatedProducts' => 'Product'
	);

	public function getCMSFields() {
		$fields = parent::getCMSFields();

		$products = $this->RelatedProducts();
		$gridField = new GridField('products', 'Related Products', $products, GridFieldConfig_RelationEditor::create());

		$fields->addFieldToTab('Root.RelatedProducts', $gridfield);
	}
}