function render_example_preprocess_page

Implements hook_preprocess_page().

Demonstrates using a preprocess function to alter the renderable array that represents the page currently being viewed.

Related topics

File

modules/render_example/render_example.module, line 95

Code

function render_example_preprocess_page(&$variables) {
    // Only modify the 'altering' page.
    if (\Drupal::routeMatch()->getRouteName() !== 'render_example.altering') {
        return;
    }
    $config = \Drupal::config('render_example.settings');
    // Preprocess hooks are invoked by the theme layer, and are used to give
    // modules a chance to manipulate the variables that are going to be made
    // available to a specific template file. Since content is still defined as
    // renderable arrays at this point you can do quite a bit to manipulate the
    // eventual output by altering these arrays.
    //
    // The $page variable in this case contains the complete content of the page
    // including all regions, and the blocks placed within each region.
    //
    // The actual process of converting a renderable array to HTML is started when
    // this variable is printed out within a Twig template. Drupal's Twig
    // extension provides a wrapper around the Twig code that prints out variables
    // which checks to see if the variable being printed is a renderable array and
    // passes it through \Drupal\Core\Render\RendererInterface::render() before
    // printing it to the screen.
    $page =& $variables['page'];
    // Move the breadcrumbs into the content area.
    if ($config->get('move_breadcrumbs') && !empty($page['breadcrumb']) && !empty($page['content'])) {
        $page['content']['breadcrumb'] = $page['breadcrumb'];
        unset($page['breadcrumb']);
        $page['content']['breadcrumb']['#weight'] = -99999;
        // Force the content to be re-sorted.
        $page['content']['#sorted'] = FALSE;
    }
    // Re-sort the contents of the sidebar in reverse order.
    if ($config->get('reverse_sidebar') && !empty($page['sidebar_first'])) {
        $page['sidebar_first'] = array_reverse($page['sidebar_first']);
        foreach (Element::children($page['sidebar_first']) as $element) {
            // Reverse the weights if they exist.
            if (!empty($page['sidebar_first'][$element]['#weight'])) {
                $page['sidebar_first'][$element]['#weight'] *= -1;
            }
        }
        // This forces the sidebar to be re-sorted.
        $page['sidebar_first']['#sorted'] = FALSE;
    }
    // Show the render array used to build the current page.
    // This relies on the Devel module's variable dumper service.
    // https://wwww.drupal.org/project/devel
    if (Drupal::moduleHandler()->moduleExists('devel') && $config->get('show_page')) {
        $page['content']['page_render_array'] = [
            '#type' => 'markup',
            '#prefix' => '<h2>' . t('The page render array') . '</h2>',
            // The devel.dumper service is provided by the devel module and makes for
            // and easier to read var_dump(). Especially if the companion Kint module
            // is enabled.
'dump' => \Drupal::service('devel.dumper')->exportAsRenderable($page, '$page'),
            '#weight' => -99999,
        ];
        $page['content']['#sorted'] = FALSE;
    }
}