class EntityAutocomplete extends Textfield {

  /**
   * {@inheritdoc}
   */
  public function getInfo() {
    $info = parent::getInfo();
    $class = get_class($this);

    // Apply default form element properties.
    $info['#target_type'] = NULL;
    $info['#selection_handler'] = 'default';
    $info['#selection_settings'] = array();
    $info['#tags'] = FALSE;
    $info['#autocreate'] = NULL;

    // This should only be set to FALSE if proper validation by the selection
    // handler is performed at another level on the extracted form values.
    $info['#validate_reference'] = TRUE;

    // IMPORTANT! This should only be set to FALSE if the #default_value
    // property is processed at another level (e.g. by a Field API widget) and
    // it's value is properly checked for access.
    $info['#process_default_value'] = TRUE;
    $info['#element_validate'] = array(
      array(
        $class,
        'validateEntityAutocomplete',
      ),
    );
    array_unshift($info['#process'], array(
      $class,
      'processEntityAutocomplete',
    ));
    return $info;
  }

  /**
   * {@inheritdoc}
   */
  public static function valueCallback(&$element, $input, FormStateInterface $form_state) {

    // Process the #default_value property.
    if ($input === FALSE && isset($element['#default_value']) && $element['#process_default_value']) {
      if (is_array($element['#default_value']) && $element['#tags'] !== TRUE) {
        throw new \InvalidArgumentException('The #default_value property is an array but the form element does not allow multiple values.');
      }
      elseif (!is_array($element['#default_value'])) {

        // Convert the default value into an array for easier processing in
        // static::getEntityLabels().
        $element['#default_value'] = array(
          $element['#default_value'],
        );
      }
      if ($element['#default_value'] && !reset($element['#default_value']) instanceof EntityInterface) {
        throw new \InvalidArgumentException('The #default_value property has to be an entity object or an array of entity objects.');
      }

      // Extract the labels from the passed-in entity objects, taking access
      // checks into account.
      return static::getEntityLabels($element['#default_value']);
    }
  }

  /**
   * Adds entity autocomplete functionality to a form element.
   *
   * @param array $element
   *   The form element to process. Properties used:
   *   - #target_type: The ID of the target entity type.
   *   - #selection_handler: The plugin ID of the entity reference selection
   *     handler.
   *   - #selection_settings: An array of settings that will be passed to the
   *     selection handler.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   * @param array $complete_form
   *   The complete form structure.
   *
   * @return array
   *   The form element.
   *
   * @throws \InvalidArgumentException
   *   Exception thrown when the #target_type or #autocreate['bundle'] are
   *   missing.
   */
  public static function processEntityAutocomplete(array &$element, FormStateInterface $form_state, array &$complete_form) {

    // Nothing to do if there is no target entity type.
    if (empty($element['#target_type'])) {
      throw new \InvalidArgumentException('Missing required #target_type parameter.');
    }

    // Provide default values and sanity checks for the #autocreate parameter.
    if ($element['#autocreate']) {
      if (!isset($element['#autocreate']['bundle'])) {
        throw new \InvalidArgumentException("Missing required #autocreate['bundle'] parameter.");
      }

      // Default the autocreate user ID to the current user.
      $element['#autocreate']['uid'] = isset($element['#autocreate']['uid']) ? $element['#autocreate']['uid'] : \Drupal::currentUser()
        ->id();
    }

    // Store the selection settings in the key/value store and pass a hashed key
    // in the route parameters.
    $selection_settings = isset($element['#selection_settings']) ? $element['#selection_settings'] : [];
    $data = serialize($selection_settings) . $element['#target_type'] . $element['#selection_handler'];
    $selection_settings_key = Crypt::hmacBase64($data, Settings::getHashSalt());
    $key_value_storage = \Drupal::keyValue('entity_autocomplete');
    if (!$key_value_storage
      ->has($selection_settings_key)) {
      $key_value_storage
        ->set($selection_settings_key, $selection_settings);
    }
    $element['#autocomplete_route_name'] = 'system.entity_autocomplete';
    $element['#autocomplete_route_parameters'] = array(
      'target_type' => $element['#target_type'],
      'selection_handler' => $element['#selection_handler'],
      'selection_settings_key' => $selection_settings_key,
    );
    return $element;
  }

  /**
   * Form element validation handler for entity_autocomplete elements.
   */
  public static function validateEntityAutocomplete(array &$element, FormStateInterface $form_state, array &$complete_form) {
    $value = NULL;
    if (!empty($element['#value'])) {
      $options = array(
        'target_type' => $element['#target_type'],
        'handler' => $element['#selection_handler'],
        'handler_settings' => $element['#selection_settings'],
      );
      $handler = \Drupal::service('plugin.manager.entity_reference_selection')
        ->getInstance($options);
      $autocreate = (bool) $element['#autocreate'] && $handler instanceof SelectionWithAutocreateInterface;
      $input_values = $element['#tags'] ? Tags::explode($element['#value']) : array(
        $element['#value'],
      );
      foreach ($input_values as $input) {
        $match = static::extractEntityIdFromAutocompleteInput($input);
        if ($match === NULL) {

          // Try to get a match from the input string when the user didn't use
          // the autocomplete but filled in a value manually.
          $match = static::matchEntityByTitle($handler, $input, $element, $form_state, !$autocreate);
        }
        if ($match !== NULL) {
          $value[] = array(
            'target_id' => $match,
          );
        }
        elseif ($autocreate) {

          // Auto-create item. See an example of how this is handled in
          // \Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem::presave().
          $value[] = array(
            'entity' => $handler
              ->createNewEntity($element['#target_type'], $element['#autocreate']['bundle'], $input, $element['#autocreate']['uid']),
          );
        }
      }

      // Check that the referenced entities are valid, if needed.
      if ($element['#validate_reference'] && !empty($value)) {

        // Validate existing entities.
        $ids = array_reduce($value, function ($return, $item) {
          if (isset($item['target_id'])) {
            $return[] = $item['target_id'];
          }
          return $return;
        });
        if ($ids) {
          $valid_ids = $handler
            ->validateReferenceableEntities($ids);
          if ($invalid_ids = array_diff($ids, $valid_ids)) {
            foreach ($invalid_ids as $invalid_id) {
              $form_state
                ->setError($element, t('The referenced entity (%type: %id) does not exist.', array(
                '%type' => $element['#target_type'],
                '%id' => $invalid_id,
              )));
            }
          }
        }

        // Validate newly created entities.
        $new_entities = array_reduce($value, function ($return, $item) {
          if (isset($item['entity'])) {
            $return[] = $item['entity'];
          }
          return $return;
        });
        if ($new_entities) {
          if ($autocreate) {
            $valid_new_entities = $handler
              ->validateReferenceableNewEntities($new_entities);
            $invalid_new_entities = array_diff_key($new_entities, $valid_new_entities);
          }
          else {

            // If the selection handler does not support referencing newly
            // created entities, all of them should be invalidated.
            $invalid_new_entities = $new_entities;
          }
          foreach ($invalid_new_entities as $entity) {
            $form_state
              ->setError($element, t('This entity (%type: %label) cannot be referenced.', array(
              '%type' => $element['#target_type'],
              '%label' => $entity
                ->label(),
            )));
          }
        }
      }

      // Use only the last value if the form element does not support multiple
      // matches (tags).
      if (!$element['#tags'] && !empty($value)) {
        $last_value = $value[count($value) - 1];
        $value = isset($last_value['target_id']) ? $last_value['target_id'] : $last_value;
      }
    }
    $form_state
      ->setValueForElement($element, $value);
  }

  /**
   * Finds an entity from an autocomplete input without an explicit ID.
   *
   * The method will return an entity ID if one single entity unambuguously
   * matches the incoming input, and sill assign form errors otherwise.
   *
   * @param string $input
   *   Single string from autocomplete element.
   * @param array $element
   *   The form element to set a form error.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current form state.
   * @param bool $strict
   *   Whether to trigger a form error if an element from $input (eg. an entity)
   *   is not found.
   *
   * @return integer|null
   *   Value of a matching entity ID, or NULL if none.
   */
  protected static function matchEntityByTitle($handler, $input, &$element, FormStateInterface $form_state, $strict) {
    $entities_by_bundle = $handler
      ->getReferenceableEntities($input, '=', 6);
    $entities = array_reduce($entities_by_bundle, function ($flattened, $bundle_entities) {
      return $flattened + $bundle_entities;
    }, []);
    $params = array(
      '%value' => $input,
      '@value' => $input,
    );
    if (empty($entities)) {
      if ($strict) {

        // Error if there are no entities available for a required field.
        $form_state
          ->setError($element, t('There are no entities matching "%value".', $params));
      }
    }
    elseif (count($entities) > 5) {
      $params['@id'] = key($entities);

      // Error if there are more than 5 matching entities.
      $form_state
        ->setError($element, t('Many entities are called %value. Specify the one you want by appending the id in parentheses, like "@value (@id)".', $params));
    }
    elseif (count($entities) > 1) {

      // More helpful error if there are only a few matching entities.
      $multiples = array();
      foreach ($entities as $id => $name) {
        $multiples[] = $name . ' (' . $id . ')';
      }
      $params['@id'] = $id;
      $form_state
        ->setError($element, t('Multiple entities match this reference; "%multiple". Specify the one you want by appending the id in parentheses, like "@value (@id)".', array(
        '%multiple' => implode('", "', $multiples),
      )));
    }
    else {

      // Take the one and only matching entity.
      return key($entities);
    }
  }

  /**
   * Converts an array of entity objects into a string of entity labels.
   *
   * This method is also responsible for checking the 'view' access on the
   * passed-in entities.
   *
   * @param \Drupal\Core\Entity\EntityInterface[] $entities
   *   An array of entity objects.
   *
   * @return string
   *   A string of entity labels separated by commas.
   */
  public static function getEntityLabels(array $entities) {
    $entity_labels = array();
    foreach ($entities as $entity) {
      $label = $entity
        ->access('view') ? $entity
        ->label() : t('- Restricted access -');

      // Take into account "autocreated" entities.
      if (!$entity
        ->isNew()) {
        $label .= ' (' . $entity
          ->id() . ')';
      }

      // Labels containing commas or quotes must be wrapped in quotes.
      $entity_labels[] = Tags::encode($label);
    }
    return implode(', ', $entity_labels);
  }

  /**
   * Extracts the entity ID from the autocompletion result.
   *
   * @param string $input
   *   The input coming from the autocompletion result.
   *
   * @return mixed|null
   *   An entity ID or NULL if the input does not contain one.
   */
  public static function extractEntityIdFromAutocompleteInput($input) {
    $match = NULL;

    // Take "label (entity id)', match the ID from parenthesis when it's a
    // number.
    if (preg_match("/.+\\((\\d+)\\)/", $input, $matches)) {
      $match = $matches[1];
    }
    elseif (preg_match("/.+\\(([\\w.]+)\\)/", $input, $matches)) {
      $match = $matches[1];
    }
    return $match;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
DependencySerializationTrait::$_serviceIds	protected	property	An array of service IDs keyed by property name used for serialization.
DependencySerializationTrait::__sleep	public	function		1
DependencySerializationTrait::__wakeup	public	function		2
EntityAutocomplete::extractEntityIdFromAutocompleteInput	public static	function	Extracts the entity ID from the autocompletion result.
EntityAutocomplete::getEntityLabels	public static	function	Converts an array of entity objects into a string of entity labels.
EntityAutocomplete::getInfo	public	function	Returns the element properties for this element. Overrides Textfield::getInfo
EntityAutocomplete::matchEntityByTitle	protected static	function	Finds an entity from an autocomplete input without an explicit ID.
EntityAutocomplete::processEntityAutocomplete	public static	function	Adds entity autocomplete functionality to a form element.
EntityAutocomplete::validateEntityAutocomplete	public static	function	Form element validation handler for entity_autocomplete elements.
EntityAutocomplete::valueCallback	public static	function	Determines how user input is mapped to an element's #value property. Overrides Textfield::valueCallback
FormElement::processAutocomplete	public static	function	Adds autocomplete functionality to elements.
FormElement::processPattern	public static	function	#process callback for #pattern form element property.
FormElement::validatePattern	public static	function	#element_validate callback for #pattern form element property.
PluginBase::$configuration	protected	property	Configuration information passed into the plugin.	2
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	Gets the base_plugin_id of the plugin instance. Overrides DerivativeInspectionInterface::getBaseId
PluginBase::getDerivativeId	public	function	Gets the derivative_id of the plugin instance. Overrides DerivativeInspectionInterface::getDerivativeId
PluginBase::getPluginDefinition	public	function	Gets the definition of the plugin implementation. Overrides PluginInspectionInterface::getPluginDefinition
PluginBase::getPluginId	public	function	Gets the plugin_id of the plugin instance. Overrides PluginInspectionInterface::getPluginId
PluginBase::__construct	public	function	Constructs a Drupal\Component\Plugin\PluginBase object.	69
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.
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.
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.	2
StringTranslationTrait::t	protected	function	Translates a string to the current language or to a given language.
Textfield::preRenderTextfield	public static	function	Prepares a #type 'textfield' render element for input.html.twig.

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class EntityAutocomplete in Zircon Profile 8

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