silverstripe-gridfieldextensions/code/GridFieldRequestHandler.php

<?php
/**
 * A base utility class for request handlers which present a grid field detail
 * view.
 *
 * This class provides some useful defaults for grid field detail views, such
 * as tabs, breadcrumbs and a back link. Much of this code is extracted from the
 * detail form.
 */
abstract class GridFieldRequestHandler extends RequestHandler {

	private static $allowed_actions = array(
		'Form'
	);

	/**
	 * @var GridField
	 */
	protected $grid;

	/**
	 * @var GridFieldComponent
	 */
	protected $component;

	/**
	 * @var string
	 */
	protected $name;

	/**
	 * @var string
	 */
	protected $template = __CLASS__;

	public function __construct(GridField $grid, GridFieldComponent $component, $name) {
		$this->grid = $grid;
		$this->component = $component;
		$this->name = $name;

		parent::__construct();
	}

	public function index($request) {
		$result = $this->renderWith($this->template);

		if($request->isAjax()) {
			return $result;
		} else {
			return $this->getTopLevelController()->customise(array(
				'Content' => $result
			));
		}
	}

	public function Link($action = null) {
		return Controller::join_links($this->grid->Link(), $this->name, $action);
	}

	/**
	 * This method should be overloaded to build out the detail form.
	 *
	 * @return Form
	 */
	public function Form() {
		$form = new Form(
			$this,
			'Form',
			new FieldList($root = new TabSet('Root', new Tab('Main'))),
			new FieldList()
		);

		if($this->getTopLevelController() instanceof LeftAndMain) {
			$form->setTemplate('LeftAndMain_EditForm');
			$form->addExtraClass('cms-content cms-edit-form cms-tabset center');
			$form->setAttribute('data-pjax-fragment', 'CurrentForm Content');

			$root->setTemplate('CMSTabSet');
			$form->Backlink = $this->getBackLink();
		}

		return $form;
	}

	/**
	 * @return Controller
	 */
	public function getController() {
		return $this->grid->getForm()->getController();
	}

	/**
	 * @param string $template
	 */
	public function setTemplate($template) {
		$this->template = $template;
	}

	/**
	 * @return string
	 */
	public function getTemplate() {
		return $this->template;
	}

	/**
	 * @return ArrayList
	 */
	public function getBreadcrumbs() {
		$controller = $this->getController();

		if($controller->hasMethod('Breadcrumbs')) {
			return $controller->Breadcrumbs();
		} else {
			return new ArrayList();
		}
	}

	/**
	 * @return string
	 */
	protected function getBackLink() {
		$controller = $this->getTopLevelController();

		if($controller->hasMethod('Backlink')) {
			return $controller->Backlink();
		} else {
			return $controller->Link();
		}
	}

	/**
	 * @return Controller
	 */
	protected function getTopLevelController() {
		$controller = $this->getController();

		while($controller) {
			if($controller instanceof GridFieldRequestHandler) {
				$controller = $controller->getController();
			} elseif($controller instanceof GridFieldDetailForm_ItemRequest) {
				$controller = $controller->getController();
			} else {
				break;
			}
		}

		return $controller;
	}

}