silverstripe-installer/mysite/code/Page.php

<?php
class Page extends SiteTree {

	public static $db = array(
	);

	public static $has_one = array(
	);

}
class Page_Controller extends ContentController {

	/**
	 * An array of actions that can be accessed via a request. Each array element should be an action name, and the
	 * permissions or conditions required to allow the user to access it.
	 *
	 * <code>
	 * array (
	 *     'action', // anyone can access this action
	 *     'action' => true, // same as above
	 *     'action' => 'ADMIN', // you must have ADMIN permissions to access this action
	 *     'action' => '->checkAction' // you can only access this action if $this->checkAction() returns true
	 * );
	 * </code>
	 *
	 * @var array
	 */
	public static $allowed_actions = array (
		'SearchForm'
	);

	public function init() {
		parent::init();

		// Note: you should use SS template require tags inside your templates 
		// instead of putting Requirements calls here.  However these are 
		// included so that our older themes still work
		Requirements::themedCSS('layout'); 
		Requirements::themedCSS('typography'); 
		Requirements::themedCSS('form'); 
	}

	/**
	 * Site search form
	 */
	function SearchForm() {
		$searchText = isset($_REQUEST['Search']) ? $_REQUEST['Search'] : 'Search';
		$fields = new FieldSet(
			new TextField('Search', '', $searchText)
		);
		$actions = new FieldSet(
			new FormAction('results', 'Search')
		);
		return new SearchForm($this, 'SearchForm', $fields, $actions);
	}

	/**
	 * Process and render search results.
	 * 
	 * @param array $data The raw request data generated from post
	 * @param SearchForm $form The form instance that was submitted
	 * @param SS_HTTPRequest $request Request generated for this action
	 */
	function results($data, $form, $request) {
		$data = array(
			'Results' => $form->getResults(),
			'Query' => $form->getSearchQuery(),
			'Title' => 'Search Results'
		);
		return $this->customise($data)->renderWith(array('Page_results', 'Page'));
	}

}