civicrm_fields_extra.module

<?php

/**
 * @file
 * Module 'civicrm_fields_extra'.
 */

/**
 * Implements hook_entity_extra_field_info().
 */
function civicrm_fields_extra_entity_extra_field_info() {

  // Fetch each CT containing civicrm fields.
  $list = _entity_fields();

  // Extra civicrm fields to be added.
  $fields = _civicrm_fields();

  foreach ($list as $civicrm_entity => $drupal_entity) {
    // Check if fields need to be added for civicrm_entity.
    if (!empty($fields[$civicrm_entity])) {

      foreach ($drupal_entity as $entity => $entity_type) {

        foreach ($entity_type as $type => $field) {

          foreach ($fields[$civicrm_entity] as $key => $value) {
            $code = "cf_" . $civicrm_entity . "_" . $entity . "_" . $type . "_" . $field . "_" . $key;
            $extra[$entity][$type]['display'][$code] = [
              'label' => '[extra] ' . $value,
              'description' => $value,
              'weight' => 0,
            ];
          }
        }
      }
    }
  }

  return $extra;
}

/**
 * Implements hook_entity_view().
 */
function civicrm_fields_extra_entity_view(array &$build, $entity, $display, $view_mode) {

  // Fetch each CT containing civicrm fields.
  $list = _entity_fields();

  // Extra civicrm fields to be added.
  $fields = _civicrm_fields();

  foreach ($list as $civicrm_entity => $drupal_entity) {
    // Check if fields need to be added for civicrm_entity.
    if (!empty($fields[$civicrm_entity])) {

      foreach ($drupal_entity as $entity_key => $entity_type) {
        // Check for this entity type.
        if ($entity_key == $entity->getEntityTypeId()) {

          foreach ($entity_type as $type => $field) {

            // Check for this bundle.
            if ($type == $entity->bundle()) {

              // Fetch civicrm id from civicrm_field.
              $id = $entity->get($field)->getString();

              // Check if value is given.
              if (!empty($id)) {
                // @todo make 'return' params generic!!!
                $civicrm_service = \Drupal::service('civicrm.service');
                $params = [
                  'return' => ['event_type', 'title', 'start_date', 'end_date'],
                  'id' => $id,
                ];
                // @todo check if api call is succesfull!!!
                $data = $civicrm_service->api($civicrm_entity, 'GetSingle', $params);
                foreach ($fields[$civicrm_entity] as $key => $value) {
                  $code = "cf_" . $civicrm_entity . "_" . $entity_key . "_" . $type . "_" . $field . "_" . $key;
                  $build[$code] = [
                    '#type' => 'markup',
                    '#markup' => $data[$key],
                  ];
                }
              }

            }
          }
        }
      }
    }
  }
}

/**
 * Define fields per CiviCRM entity.
 */
function _civicrm_fields() {
  return [
    'event' => [
      'event_title' => 'Title',
    ],
  ];
}

/**
 * Return all Drupal entities containing civicrm_fields.
 */
function _entity_fields() {
  $list = [];
  $entity_manager = \Drupal::service('entity_field.manager');
  $field_map = $entity_manager->getFieldMap();
  foreach ($field_map as $entity_type => $entity_fields) {
    foreach ($entity_fields as $field_key => $field) {
      // Find civicrm_field_contact.
      if ($field['type'] == 'civicrm_field_contact') {
        foreach ($field['bundles'] as $bundle) {
          $list['contact'][$entity_type][$bundle] = $field_key;
        }
      }
      // Find civicrm_field_event.
      if ($field['type'] == 'civicrm_field_event') {
        foreach ($field['bundles'] as $bundle) {
          $list['event'][$entity_type][$bundle] = $field_key;
        }
      }
      // Find civicrm_field_contribution_page.
      if ($field['type'] == 'civicrm_field_contribution_page') {
        foreach ($field['bundles'] as $bundle) {
          $list['contribution_page'][$entity_type][$bundle] = $field_key;
        }
      }
    }
  }
  return $list;
}