abstract class RenderElement in Drupal 10

Provides a base class for render element plugins.

Render elements are referenced in render arrays; see the Render API topic for an overview of render arrays and render elements.

The elements of render arrays are divided up into properties (whose keys start with #) and children (whose keys do not start with #). The properties provide data or settings that are used in rendering. Some properties are specific to a particular type of render element, some are available for any render element, and some are available for any form input element. A list of the properties that are available for all render elements follows; the properties that are for all form elements are documented on \Drupal\Core\Render\Element\FormElement, and properties specific to a particular element are documented on that element's class. See the Render API topic for a list of the most commonly-used properties.

Many of the properties are strings that are displayed to users. These strings, if they are literals provided by your module, should be internationalized and translated; see the Internationalization topic for more information. Note that although in the properties list that follows, they are designated to be of type string, they would generally end up being \Drupal\Core\StringTranslation\TranslatableMarkup objects instead.

Here is the list of the properties used during the rendering of all render elements:

• #access: (bool) Whether the element is accessible or not. When FALSE, the element is not rendered and user-submitted values are not taken into consideration.
• #access_callback: A callable or function name to call to check access. Argument: element.
• #allowed_tags: (array) Array of allowed HTML tags for XSS filtering of #markup, #prefix, #suffix, etc.
• #attached: (array) Array of attachments associated with the element. See the "Attaching libraries in render arrays" section of the Render API topic for an overview, and \Drupal\Core\Render\AttachmentsResponseProcessorInterface::processAttachments for a list of what this can contain. Besides this list, it may also contain a 'placeholders' element; see the Placeholders section of the Render API topic for an overview.
• #attributes: (array) HTML attributes for the element. The first-level keys are the attribute names, such as 'class', and the attributes are usually given as an array of string values to apply to that attribute (the rendering system will concatenate them together into a string in the HTML output).
• #cache: (array) Cache information. See the Caching section of the Render API topic for more information.
• #children: (array, internal) Array of child elements of this element. Set and used during the rendering process.
• #create_placeholder: (bool) TRUE if the element has placeholders that are generated by #lazy_builder callbacks. Set internally during rendering in some cases. See also #attached.
• #defaults_loaded: (bool) Set to TRUE during rendering when the defaults for the element #type have been added to the element.
• #value: (mixed) A value that cannot be edited by the user.
• #has_garbage_value: (bool) Internal only. Set to TRUE to indicate that the #value property of an element should not be used or processed.
• #id: (string) The HTML ID on the element. This is automatically set for form elements, but not for all render elements; you can override the default value or add an ID by setting this property.
• #lazy_builder: (array) Array whose first element is a lazy building callback (callable), and whose second is an array of scalar arguments to the callback. To use lazy building, the element array must be very simple: no properties except #lazy_builder, #cache, #weight, and #create_placeholder, and no children. A lazy builder callback typically generates #markup and/or placeholders; see the Placeholders section of the Render API topic for information about placeholders.
• #markup: (string) During rendering, this will be set to the HTML markup output. It can also be set on input, as a fallback if there is no theming for the element. This will be filtered for XSS problems during rendering; see also #plain_text and #allowed_tags.
• #plain_text: (string) Elements can set this instead of #markup. All HTML tags will be escaped in this text, and if both #plain_text and #markup are provided, #plain_text is used.
• #post_render: (array) Array of callables or function names, which are called after the element is rendered. Arguments: rendered element string, children.
• #pre_render: (array) Array of callables or function names, which are called just before the element is rendered. Argument: $element. Return value: an altered $element.
• #prefix: (string) Text to render before the entire element output. See also #suffix. If it is not already wrapped in a safe markup object, will be filtered for XSS safety.
• #printed: (bool, internal) Set to TRUE when an element and its children have been rendered.
• #render_children: (bool, internal) Set to FALSE by the rendering process if the #theme call should be bypassed (normally, the theme is used to render the children). Set to TRUE by the rendering process if the children should be rendered by rendering each one separately and concatenating.
• #suffix: (string) Text to render after the entire element output. See also #prefix. If it is not already wrapped in a safe markup object, will be filtered for XSS safety.
• #theme: (string) Name of the theme hook to use to render the element. A default is generally set for elements; users of the element can override this (typically by adding __suggestion suffixes).
• #theme_wrappers: (array) Array of theme hooks, which are invoked after the element and children are rendered, and before #post_render functions.
• #type: (string) The machine name of the type of render/form element.
• #weight: (float) The sort order for rendering, with lower numbers coming before higher numbers. Default if not provided is zero; elements with the same weight are rendered in the order they appear in the render array.

Hierarchy

• class \Drupal\Component\Plugin\PluginBase implements DerivativeInspectionInterface, PluginInspectionInterface
  • class \Drupal\Core\Plugin\PluginBase uses DependencySerializationTrait, MessengerTrait, StringTranslationTrait
    • class \Drupal\Core\Render\Element\RenderElement implements ElementInterface

See also

\Drupal\Core\Render\Annotation\RenderElement

\Drupal\Core\Render\ElementInterface

\Drupal\Core\Render\ElementInfoManager

Plugin API

Related topics

Render API overview

Overview of the Theme system and Render API.

14 files declare their use of RenderElement

BreakLockLink.php in core/lib/Drupal/Core/TempStore/Element/BreakLockLink.php

ContextualLinks.php in core/modules/contextual/src/Element/ContextualLinks.php

ContextualLinksPlaceholder.php in core/modules/contextual/src/Element/ContextualLinksPlaceholder.php

form.inc in core/includes/form.inc

Functions for form and batch generation and processing.

LayoutBuilder.php in core/modules/layout_builder/src/Element/LayoutBuilder.php

... See full list

File

core/lib/Drupal/Core/Render/Element/RenderElement.php, line 127

Namespace

Drupal\Core\Render\Element

abstract class RenderElement extends PluginBase implements ElementInterface {

  /**
   * {@inheritdoc}
   */
  public static function setAttributes(&$element, $class = []) {
    if (!empty($class)) {
      if (!isset($element['#attributes']['class'])) {
        $element['#attributes']['class'] = [];
      }
      $element['#attributes']['class'] = array_merge($element['#attributes']['class'], $class);
    }

    // This function is invoked from form element theme functions, but the
    // rendered form element may not necessarily have been processed by
    // \Drupal::formBuilder()->doBuildForm().
    if (!empty($element['#required'])) {
      $element['#attributes']['class'][] = 'required';
      $element['#attributes']['required'] = 'required';
      $element['#attributes']['aria-required'] = 'true';
    }
    if (isset($element['#parents']) && isset($element['#errors']) && !empty($element['#validated'])) {
      $element['#attributes']['class'][] = 'error';
      $element['#attributes']['aria-invalid'] = 'true';
    }
  }

  /**
   * Adds members of this group as actual elements for rendering.
   *
   * @param array $element
   *   An associative array containing the properties and children of the
   *   element.
   *
   * @return array
   *   The modified element with all group members.
   */
  public static function preRenderGroup($element) {

    // The element may be rendered outside of a Form API context.
    if (!isset($element['#parents']) || !isset($element['#groups'])) {
      return $element;
    }

    // Inject group member elements belonging to this group.
    $parents = implode('][', $element['#parents']);
    $children = Element::children($element['#groups'][$parents]);
    if (!empty($children)) {
      foreach ($children as $key) {

        // Break references and indicate that the element should be rendered as
        // group member.
        $child = (array) $element['#groups'][$parents][$key];
        $child['#group_details'] = TRUE;

        // Inject the element as new child element.
        $element[] = $child;
        $sort = TRUE;
      }

      // Re-sort the element's children if we injected group member elements.
      if (isset($sort)) {
        $element['#sorted'] = FALSE;
      }
    }
    if (isset($element['#group'])) {

      // Contains form element summary functionalities.
      $element['#attached']['library'][] = 'core/drupal.form';
      $group = $element['#group'];

      // If this element belongs to a group, but the group-holding element does
      // not exist, we need to render it (at its original location).
      if (!isset($element['#groups'][$group]['#group_exists'])) {

        // Intentionally empty to clarify the flow; we simply return $element.
      }
      elseif (!empty($element['#group_details'])) {

        // Intentionally empty to clarify the flow; we simply return $element.
      }
      elseif (Element::children($element['#groups'][$group])) {
        $element['#printed'] = TRUE;
      }
    }
    return $element;
  }

  /**
   * Form element processing handler for the #ajax form property.
   *
   * This method is useful for non-input elements that can be used in and
   * outside the context of a form.
   *
   * @param array $element
   *   An associative array containing the properties of the element.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   * @param array $complete_form
   *   The complete form structure.
   *
   * @return array
   *   The processed element.
   *
   * @see self::preRenderAjaxForm()
   */
  public static function processAjaxForm(&$element, FormStateInterface $form_state, &$complete_form) {
    return static::preRenderAjaxForm($element);
  }

  /**
   * Adds Ajax information about an element to communicate with JavaScript.
   *
   * If #ajax is set on an element, this additional JavaScript is added to the
   * page header to attach the Ajax behaviors. See ajax.js for more information.
   *
   * @param array $element
   *   An associative array containing the properties of the element.
   *   Properties used:
   *   - #ajax['event']
   *   - #ajax['prevent']
   *   - #ajax['url']
   *   - #ajax['callback']
   *   - #ajax['options']
   *   - #ajax['wrapper']
   *   - #ajax['parameters']
   *   - #ajax['effect']
   *   - #ajax['accepts']
   *
   * @return array
   *   The processed element with the necessary JavaScript attached to it.
   */
  public static function preRenderAjaxForm($element) {

    // Skip already processed elements.
    if (isset($element['#ajax_processed'])) {
      return $element;
    }

    // Initialize #ajax_processed, so we do not process this element again.
    $element['#ajax_processed'] = FALSE;

    // Nothing to do if there are no Ajax settings.
    if (empty($element['#ajax'])) {
      return $element;
    }

    // Add a data attribute to disable automatic refocus after ajax call.
    if (!empty($element['#ajax']['disable-refocus'])) {
      $element['#attributes']['data-disable-refocus'] = "true";
    }

    // Add a reasonable default event handler if none was specified.
    if (isset($element['#ajax']) && !isset($element['#ajax']['event'])) {
      switch ($element['#type']) {
        case 'submit':
        case 'button':
        case 'image_button':

          // Pressing the ENTER key within a textfield triggers the click event of
          // the form's first submit button. Triggering Ajax in this situation
          // leads to problems, like breaking autocomplete textfields, so we bind
          // to mousedown instead of click.
          // @see https://www.drupal.org/node/216059
          $element['#ajax']['event'] = 'mousedown';

          // Retain keyboard accessibility by setting 'keypress'. This causes
          // ajax.js to trigger 'event' when SPACE or ENTER are pressed while the
          // button has focus.
          $element['#ajax']['keypress'] = TRUE;

          // Binding to mousedown rather than click means that it is possible to
          // trigger a click by pressing the mouse, holding the mouse button down
          // until the Ajax request is complete and the button is re-enabled, and
          // then releasing the mouse button. Set 'prevent' so that ajax.js binds
          // an additional handler to prevent such a click from triggering a
          // non-Ajax form submission. This also prevents a textfield's ENTER
          // press triggering this button's non-Ajax form submission behavior.
          if (!isset($element['#ajax']['prevent'])) {
            $element['#ajax']['prevent'] = 'click';
          }
          break;
        case 'password':
        case 'textfield':
        case 'number':
        case 'tel':
        case 'textarea':
          $element['#ajax']['event'] = 'blur';
          break;
        case 'radio':
        case 'checkbox':
        case 'select':
        case 'date':
          $element['#ajax']['event'] = 'change';
          break;
        case 'link':
          $element['#ajax']['event'] = 'click';
          break;
        default:
          return $element;
      }
    }

    // Attach JavaScript settings to the element.
    if (isset($element['#ajax']['event'])) {
      $element['#attached']['library'][] = 'core/internal.jquery.form';
      $element['#attached']['library'][] = 'core/drupal.ajax';
      $settings = $element['#ajax'];

      // Assign default settings. When 'url' is set to NULL, ajax.js submits the
      // Ajax request to the same URL as the form or link destination is for
      // someone with JavaScript disabled. This is generally preferred as a way to
      // ensure consistent server processing for js and no-js users, and Drupal's
      // content negotiation takes care of formatting the response appropriately.
      // However, 'url' and 'options' may be set when wanting server processing
      // to be substantially different for a JavaScript triggered submission.
      $settings += [
        'url' => NULL,
        'options' => [
          'query' => [],
        ],
        'dialogType' => 'ajax',
      ];
      if (array_key_exists('callback', $settings) && !isset($settings['url'])) {
        $settings['url'] = Url::fromRoute('<current>');

        // Add all the current query parameters in order to ensure that we build
        // the same form on the AJAX POST requests. For example,
        // \Drupal\user\AccountForm takes query parameters into account in order
        // to hide the password field dynamically.
        $settings['options']['query'] += \Drupal::request()->query
          ->all();
        $settings['options']['query'][FormBuilderInterface::AJAX_FORM_REQUEST] = TRUE;
      }

      // @todo Legacy support. Remove in Drupal 8.
      if (isset($settings['method']) && $settings['method'] == 'replace') {
        $settings['method'] = 'replaceWith';
      }

      // Convert \Drupal\Core\Url object to string.
      if (isset($settings['url']) && $settings['url'] instanceof Url) {
        $url = $settings['url']
          ->setOptions($settings['options'])
          ->toString(TRUE);
        BubbleableMetadata::createFromRenderArray($element)
          ->merge($url)
          ->applyTo($element);
        $settings['url'] = $url
          ->getGeneratedUrl();
      }
      else {
        $settings['url'] = NULL;
      }
      unset($settings['options']);

      // Add special data to $settings['submit'] so that when this element
      // triggers an Ajax submission, Drupal's form processing can determine which
      // element triggered it.
      // @see _form_element_triggered_scripted_submission()
      if (isset($settings['trigger_as'])) {

        // An element can add a 'trigger_as' key within #ajax to make the element
        // submit as though another one (for example, a non-button can use this
        // to submit the form as though a button were clicked). When using this,
        // the 'name' key is always required to identify the element to trigger
        // as. The 'value' key is optional, and only needed when multiple elements
        // share the same name, which is commonly the case for buttons.
        $settings['submit']['_triggering_element_name'] = $settings['trigger_as']['name'];
        if (isset($settings['trigger_as']['value'])) {
          $settings['submit']['_triggering_element_value'] = $settings['trigger_as']['value'];
        }
        unset($settings['trigger_as']);
      }
      elseif (isset($element['#name'])) {

        // Most of the time, elements can submit as themselves, in which case the
        // 'trigger_as' key isn't needed, and the element's name is used.
        $settings['submit']['_triggering_element_name'] = $element['#name'];

        // If the element is a (non-image) button, its name may not identify it
        // uniquely, in which case a match on value is also needed.
        // @see _form_button_was_clicked()
        if (!empty($element['#is_button']) && empty($element['#has_garbage_value'])) {
          $settings['submit']['_triggering_element_value'] = $element['#value'];
        }
      }

      // Convert a simple #ajax['progress'] string into an array.
      if (isset($settings['progress']) && is_string($settings['progress'])) {
        $settings['progress'] = [
          'type' => $settings['progress'],
        ];
      }

      // Change progress path to a full URL.
      if (isset($settings['progress']['url']) && $settings['progress']['url'] instanceof Url) {
        $settings['progress']['url'] = $settings['progress']['url']
          ->toString();
      }
      $element['#attached']['drupalSettings']['ajax'][$element['#id']] = $settings;
      $element['#attached']['drupalSettings']['ajaxTrustedUrl'][$settings['url']] = TRUE;

      // Indicate that Ajax processing was successful.
      $element['#ajax_processed'] = TRUE;
    }
    return $element;
  }

  /**
   * Arranges elements into groups.
   *
   * This method is useful for non-input elements that can be used in and
   * outside the context of a form.
   *
   * @param array $element
   *   An associative array containing the properties and children of the
   *   element. Note that $element must be taken by reference here, so processed
   *   child elements are taken over into $form_state.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   * @param array $complete_form
   *   The complete form structure.
   *
   * @return array
   *   The processed element.
   */
  public static function processGroup(&$element, FormStateInterface $form_state, &$complete_form) {
    $parents = implode('][', $element['#parents']);

    // Each details element forms a new group. The #type 'vertical_tabs' basically
    // only injects a new details element.
    $groups =& $form_state
      ->getGroups();
    $groups[$parents]['#group_exists'] = TRUE;
    $element['#groups'] =& $groups;

    // Process vertical tabs group member details elements.
    if (isset($element['#group'])) {

      // Add this details element to the defined group (by reference).
      $group = $element['#group'];
      $groups[$group][] =& $element;
    }
    return $element;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
DependencySerializationTrait::$_entityStorages	protected	property
DependencySerializationTrait::$_serviceIds	protected	property
DependencySerializationTrait::__sleep	public	function		2
DependencySerializationTrait::__wakeup	public	function		2
ElementInterface::getInfo	public	function	Returns the element properties for this element.	56
MessengerTrait::$messenger	protected	property	The messenger.	18
MessengerTrait::messenger	public	function	Gets the messenger.	18
MessengerTrait::setMessenger	public	function	Sets the messenger.
PluginBase::$configuration	protected	property	Configuration information passed into the plugin.	1
PluginBase::$pluginDefinition	protected	property	The plugin implementation definition.
PluginBase::$pluginId	protected	property	The plugin_id.
PluginBase::DERIVATIVE_SEPARATOR		constant	A string which is used to separate base plugin IDs from the derivative ID.
PluginBase::getBaseId	public	function
PluginBase::getDerivativeId	public	function
PluginBase::getPluginDefinition	public	function		2
PluginBase::getPluginId	public	function
PluginBase::isConfigurable	public	function	Determines if the plugin is configurable.
PluginBase::__construct	public	function	Constructs a \Drupal\Component\Plugin\PluginBase object.	53
RenderElement::preRenderAjaxForm	public static	function	Adds Ajax information about an element to communicate with JavaScript.
RenderElement::preRenderGroup	public static	function	Adds members of this group as actual elements for rendering.
RenderElement::processAjaxForm	public static	function	Form element processing handler for the #ajax form property.	1
RenderElement::processGroup	public static	function	Arranges elements into groups.
RenderElement::setAttributes	public static	function	Sets a form element's class attribute. Overrides ElementInterface::setAttributes
StringTranslationTrait::$stringTranslation	protected	property	The string translation service.	3
StringTranslationTrait::formatPlural	protected	function	Formats a string containing a count of items.
StringTranslationTrait::getNumberOfPlurals	protected	function	Returns the number of plurals supported by a given language.
StringTranslationTrait::getStringTranslation	protected	function	Gets the string translation service.
StringTranslationTrait::setStringTranslation	public	function	Sets the string translation service to use.	1
StringTranslationTrait::t	protected	function	Translates a string to the current language or to a given language.