public static function RenderExampleController::preRender in Examples for Developers 8

Same name and namespace in other branches

3.x modules/render_example/src/Controller/RenderExampleController.php \Drupal\render_example\Controller\RenderExampleController::preRender()

A #pre_render callback, expand array to include additional example info.

This method is called during the process of rendering the array generated by \Drupal\render_example\Controller\RenderExampleController::arrays().

This also demonstrates how a #pre_render callback could be used to expand a relatively simple array into multiple individual renderable elements based on application logic.

Parameters

array $element: Pre render methods (and functions) get a single argument that is the render API array representing the element where the #pre_render property was defined, and all of it's children.

Return value

array Pre render methods (and functions) should return the modified render array.

File

render_example/src/Controller/RenderExampleController.php, line 439

Class

RenderExampleController: Provides module description page and examples of building render arrays.

Namespace

Drupal\render_example\Controller

Code

public static function preRender(array $element) {

  // For each first level child element lets add some additional helpful
  // output. \Drupal\Core\Render\Element::children() is a utility method that
  // allows you to quickly identify all children of a render array. That is
  // those key/value pairs whose key does not start with a '#'.
  foreach (Element::children($element) as $key) {
    $child = $element[$key];
    unset($element[$key]);
    if (isset($child['#description'])) {
      $element[$key] = [
        // The value from the #description property will be used as a title
        // for this element in the final output.
        'description' => [
          '#markup' => $child['#description'],
        ],
        // Move the original element to 'rendered'. The rendering process is
        // recursive so this will still be located, and rendered to HTML.
        'rendered' => $child,
        // Export the element definition as a string of text so we can display
        // the array that was used to create the rendered output just below
        // the output.
        'unrendered' => [
          '#markup' => htmlentities(Variable::export($child)),
        ],
        '#theme' => 'render_array',
      ];
    }
  }

  // Return our modified version of the original $element.
  return $element;
}

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