How is a CMS page rendered?

dmitry_fedyuk · May 4, 2017, 10:35pm

Step 1. Routing

Details: How is the CMS frontend router (Magento\Cms\Controller\Router) implemented?

Step 2. Magento\Cms\Controller\Page\View::execute()

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Controller/Page/View.php#L28-L42


/**
 * View CMS page action
 *
 * @return \Magento\Framework\Controller\ResultInterface
 */
public function execute()
{
    $pageId = $this->getRequest()->getParam('page_id', $this->getRequest()->getParam('id', false));
    $resultPage = $this->_objectManager->get('Magento\Cms\Helper\Page')->prepareResultPage($this, $pageId);
    if (!$resultPage) {
        $resultForward = $this->resultForwardFactory->create();
        return $resultForward->forward('noroute');
    }
    return $resultPage;
}

Please note that the page is instantiated using the Magento\Framework\ObjectManagerInterface::get() method, so the page is a singleton, and this object will be used later by the Magento\Cms\Block\Page block.

Step 3. Magento\Cms\Helper\Page::prepareResultPage(). Loading the page from the database.

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Helper/Page.php#L115-L122


/**
 * Return result CMS page
 *
 * @param Action $action
 * @param null $pageId
 * @return \Magento\Framework\View\Result\Page|bool
 */
public function prepareResultPage(Action $action, $pageId = null)

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Helper/Page.php#L124-L150


if ($pageId !== null && $pageId !== $this->_page->getId()) {
    $delimiterPosition = strrpos($pageId, '|');
    if ($delimiterPosition) {
        $pageId = substr($pageId, 0, $delimiterPosition);
    }


    $this->_page->setStoreId($this->_storeManager->getStore()->getId());
    if (!$this->_page->load($pageId)) {
        return false;
    }
}


if (!$this->_page->getId()) {
    return false;
}


$inRange = $this->_localeDate->isScopeDateInInterval(
    null,
    $this->_page->getCustomThemeFrom(),
    $this->_page->getCustomThemeTo()
);


if ($this->_page->getCustomTheme()) {
    if ($inRange) {
        $this->_design->setDesignTheme($this->_page->getCustomTheme());
    }
}

Step 4. Creating the resulting instance of Magento\Framework\View\Result\Page

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Helper/Page.php#L151-L152


/** @var \Magento\Framework\View\Result\Page $resultPage */
$resultPage = $this->resultPageFactory->create();

Step 4.1. Magento\Framework\View\Result\PageFactory::create()

github.com

magento/magento2/blob/2.1.6/lib/internal/Magento/Framework/View/Result/PageFactory.php#L42-L61


/**
 * Create new page regarding its type
 *
 * TODO: As argument has to be controller action interface, temporary solution until controller output models
 * TODO: are not implemented
 *
 * @param bool $isView
 * @param array $arguments
 * @return \Magento\Framework\View\Result\Page
 */
public function create($isView = false, array $arguments = [])
{
    /** @var \Magento\Framework\View\Result\Page $page */
    $page = $this->objectManager->create($this->instanceName, $arguments);
    // TODO Temporary solution for compatibility with View object. Will be deleted in MAGETWO-28359
    if (!$isView) {
        $page->addDefaultHandle();
    }
    return $page;
}

Step 5. Magento\Cms\Helper\Page::setLayoutType()

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Helper/Page.php#L204-L225


/**
 * Set layout type
 *
 * @param bool $inRange
 * @param \Magento\Framework\View\Result\Page $resultPage
 * @return \Magento\Framework\View\Result\Page
 */
protected function setLayoutType($inRange, $resultPage)
{
    if ($this->_page->getPageLayout()) {
        if ($this->_page->getCustomPageLayout()
            && $this->_page->getCustomPageLayout() != 'empty'
            && $inRange
        ) {
            $handle = $this->_page->getCustomPageLayout();
        } else {
            $handle = $this->_page->getPageLayout();
        }
        $resultPage->getConfig()->setPageLayout($handle);
    }
    return $resultPage;
}

Step 6. Layout handles setup

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Helper/Page.php#L154-L169


$resultPage->addHandle('cms_page_view');
$resultPage->addPageLayoutHandles(['id' => $this->_page->getIdentifier()]);


$this->_eventManager->dispatch(
    'cms_page_render',
    ['page' => $this->_page, 'controller_action' => $action]
);


if ($this->_page->getCustomLayoutUpdateXml() && $inRange) {
    $layoutUpdate = $this->_page->getCustomLayoutUpdateXml();
} else {
    $layoutUpdate = $this->_page->getLayoutUpdateXml();
}
if (!empty($layoutUpdate)) {
    $resultPage->getLayout()->getUpdate()->addUpdate($layoutUpdate);
}

Step 7. The layout building.

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Helper/Page.php#L171-L177


$contentHeadingBlock = $resultPage->getLayout()->getBlock('page_content_heading');
if ($contentHeadingBlock) {
    $contentHeading = $this->_escaper->escapeHtml($this->_page->getContentHeading());
    $contentHeadingBlock->setContentHeading($contentHeading);
}


return $resultPage;

This code looks like just the page_content_heading block setup (this block is not used for the «About us» page), but really any call for the Magento\Framework\View\Layout::getBlock() method builds the layout (if it is not yet built):

github.com

magento/magento2/blob/2.1.6/lib/internal/Magento/Framework/View/Layout.php#L851-L865


/**
 * Get block object by name
 *
 * @param string $name
 * @return \Magento\Framework\View\Element\AbstractBlock|bool
 */
public function getBlock($name)
{
    $this->build();
    if (isset($this->_blocks[$name])) {
        return $this->_blocks[$name];
    } else {
        return false;
    }
}

Step 8. Magento\Cms\Block\Page::__construct()

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Block/Page.php#L45-L72


/**
 * Construct
 *
 * @param \Magento\Framework\View\Element\Context $context
 * @param \Magento\Cms\Model\Page $page
 * @param \Magento\Cms\Model\Template\FilterProvider $filterProvider
 * @param \Magento\Store\Model\StoreManagerInterface $storeManager
 * @param \Magento\Cms\Model\PageFactory $pageFactory
 * @param \Magento\Framework\View\Page\Config $pageConfig
 * @param array $data
 */
public function __construct(
    \Magento\Framework\View\Element\Context $context,
    \Magento\Cms\Model\Page $page,
    \Magento\Cms\Model\Template\FilterProvider $filterProvider,
    \Magento\Store\Model\StoreManagerInterface $storeManager,
    \Magento\Cms\Model\PageFactory $pageFactory,
    \Magento\Framework\View\Page\Config $pageConfig,
    array $data = []
) {
    parent::__construct($context, $data);
    // used singleton (instead factory) because there exist dependencies on \Magento\Cms\Helper\Page
    $this->_page = $page;
    $this->_filterProvider = $filterProvider;
    $this->_storeManager = $storeManager;
    $this->_pageFactory = $pageFactory;
    $this->pageConfig = $pageConfig;
}

The $page is the singleton was created on the Step 2.

Step 9. Magento\Cms\Block\Page::_prepareLayout()

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Block/Page.php#L94-L116


/**
 * Prepare global layout
 *
 * @return $this
 */
protected function _prepareLayout()
{
    $page = $this->getPage();
    $this->_addBreadcrumbs($page);
    $this->pageConfig->addBodyClass('cms-' . $page->getIdentifier());
    $metaTitle = $page->getMetaTitle();
    $this->pageConfig->getTitle()->set($metaTitle ? $metaTitle : $page->getTitle());
    $this->pageConfig->setKeywords($page->getMetaKeywords());
    $this->pageConfig->setDescription($page->getMetaDescription());


    $pageMainTitle = $this->getLayout()->getBlock('page.main.title');
    if ($pageMainTitle) {
        // Setting empty page title if content heading is absent
        $cmsTitle = $page->getContentHeading() ?: ' ';
        $pageMainTitle->setPageTitle($this->escapeHtml($cmsTitle));
    }
    return parent::_prepareLayout();
}

Step 10. Magento\Cms\Block\Page::_addBreadcrumbs()

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Block/Page.php#L118-L148


/**
 * Prepare breadcrumbs
 *
 * @param \Magento\Cms\Model\Page $page
 * @throws \Magento\Framework\Exception\LocalizedException
 * @return void
 */
protected function _addBreadcrumbs(\Magento\Cms\Model\Page $page)
{
    if ($this->_scopeConfig->getValue('web/default/show_cms_breadcrumbs', ScopeInterface::SCOPE_STORE)
        && ($breadcrumbsBlock = $this->getLayout()->getBlock('breadcrumbs'))
        && $page->getIdentifier() !== $this->_scopeConfig->getValue(
            'web/default/cms_home_page',
            ScopeInterface::SCOPE_STORE
        )
        && $page->getIdentifier() !== $this->_scopeConfig->getValue(
            'web/default/cms_no_route',
            ScopeInterface::SCOPE_STORE
        )
    ) {
        $breadcrumbsBlock->addCrumb(
            'home',
            [
                'label' => __('Home'),
                'title' => __('Go to Home Page'),
                'link' => $this->_storeManager->getStore()->getBaseUrl()
            ]
        );
        $breadcrumbsBlock->addCrumb('cms_page', ['label' => $page->getTitle(), 'title' => $page->getTitle()]);
    }
}

Step 11. Magento\Cms\Controller\Page\View::execute() finish

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Controller/Page/View.php#L37-L41


if (!$resultPage) {
    $resultForward = $this->resultForwardFactory->create();
    return $resultForward->forward('noroute');
}
return $resultPage;

Step 12. Magento\Framework\App\Action\Action::dispatch() finish

github.com

magento/magento2/blob/2.1.6/lib/internal/Magento/Framework/App/Action/Action.php#L102-L119


    $result = $this->execute();
    \Magento\Framework\Profiler::start('postdispatch');
    if (!$this->_actionFlag->get('', self::FLAG_NO_POST_DISPATCH)) {
        $this->_eventManager->dispatch(
            'controller_action_postdispatch_' . $request->getFullActionName(),
            $eventParameters
        );
        $this->_eventManager->dispatch(
            'controller_action_postdispatch_' . $request->getRouteName(),
            $eventParameters
        );
        $this->_eventManager->dispatch('controller_action_postdispatch', $eventParameters);
    }
    \Magento\Framework\Profiler::stop('postdispatch');
    \Magento\Framework\Profiler::stop('action_body');
}
\Magento\Framework\Profiler::stop($profilerKey);
return $result ?: $this->_response;

Step 13. Magento\Framework\App\FrontController::dispatch() finish

github.com

magento/magento2/blob/2.1.6/lib/internal/Magento/Framework/App/FrontController.php#L55-L73


                    $result = $actionInstance->dispatch($request);
                } else {
                    $result = $actionInstance->execute();
                }
                break;
            }
        } catch (\Magento\Framework\Exception\NotFoundException $e) {
            $request->initForward();
            $request->setActionName('noroute');
            $request->setDispatched(false);
            break;
        }
    }
}
\Magento\Framework\Profiler::stop('routers_match');
if ($routingCycleCounter > 100) {
    throw new \LogicException('Front controller reached 100 router match iterations');
}
return $result;

Step 14. Returning to Magento\Framework\App\Http::launch(). Starting the page rendering

github.com

magento/magento2/blob/2.1.6/lib/internal/Magento/Framework/App/Http.php#L135-L139


$result = $frontController->dispatch($this->_request);
// TODO: Temporary solution until all controllers return ResultInterface (MAGETWO-28359)
if ($result instanceof ResultInterface) {
    $this->registry->register('use_page_cache_plugin', true, true);
    $result->renderResult($this->_response);

Step 15. Magento\Framework\View\Result\Layout::renderResult()

github.com

magento/magento2/blob/2.1.6/lib/internal/Magento/Framework/View/Result/Layout.php#L152-L171


/**
 * Render current layout
 *
 * @param ResponseInterface $response
 * @return $this
 */
public function renderResult(ResponseInterface $response)
{
    \Magento\Framework\Profiler::start('LAYOUT');
    \Magento\Framework\Profiler::start('layout_render');


    $this->applyHttpHeaders($response);
    $this->render($response);


    $this->eventManager->dispatch('layout_render_before');
    $this->eventManager->dispatch('layout_render_before_' . $this->request->getFullActionName());
    \Magento\Framework\Profiler::stop('layout_render');
    \Magento\Framework\Profiler::stop('LAYOUT');
    return $this;
}

Step 16. Magento\Framework\View\Result\Page::render()

Step 17. Magento_Cms/view/frontend/layout/cms_page_view.xml

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/view/frontend/layout/cms_page_view.xml#L9-L13


<body>
    <referenceContainer name="content">
        <block class="Magento\Cms\Block\Page" name="cms_page"/>
    </referenceContainer>
</body>

Step 18. Magento\Cms\Block\Page::_toHtml()

The block was constructed on the Step 8.

github.com

magento/magento2/blob/2.1.6/app/code/Magento/Cms/Block/Page.php#L150-L159


/**
 * Prepare HTML content
 *
 * @return string
 */
protected function _toHtml()
{
    $html = $this->_filterProvider->getPageFilter()->filter($this->getPage()->getContent());
    return $html;
}

dmitry_fedyuk · May 4, 2017, 10:36pm