d8challenge.md

Problem:

• I want to render an entity using an entity_reference field formatter. This entity is independent and not a field value, so it doesn't have any parent. I want to give the end user the options of formatters to pick from and be able to fill in options.
• If it helps think of it as you have a file entity and you want to render it using the file_generic formatter.

Context:

• Rendering an entity embedded in filtered text (hence rendering is done in Filter plugins).

field_items_render.php

<?php

// Render a file using the 'Generic file' formatter (a nice link with an icon):
$file = file_load(1);
$field = array('type' => 'file');
// File fields are stupid with their field values.
$items = array(0 => array('fid' => $file->fid) + (array) $file);
$display = array('type' => 'file_default');
$output = field_items_render($field, array(), $items, $display);
return drupal_render($output);

function field_items_render(array $field, array $instance, array $items, array $display, $langcode = LANGUAGE_NONE) {
  $field += field_info_field_types($field['type']);

  $display += field_info_formatter_types($display['type']);

  $instance += array(
    'entity_type' => 'node',
    'bundle' => '_fake',
    'settings' => array(),
  );
  $instance['settings'] += $field['instance_settings'];

  $entity_type = 'node';
  $entity = NULL;
  $entities = array(0 => $entity);
  $entity_items = array(0 => &$items);

  // Run hook_field_prepare_view() on the field module.
  $function = $field['module'] . '_field_prepare_view';
  if (function_exists($function)) {
    $function($entity_type, $entities, $field, $instances, $langcode, $entity_items);
  }

  // Run hook_field_formatter_prepare_view() on the formatter module.
  $function = $display['module'] . '_field_formatter_prepare_view';
  if (function_exists($function)) {
    $function($entity_type, $entities, $field, array(0 => $instance), $langcode, $entity_items, array(0 => $display));
  }

  // Run hook_field_formatter_View() on the formatter module.
  $function = $display['module'] . '_field_formatter_view';
  $result = $function($entity_type, NULL, $field, $instance, $langcode, $items, $display);

  return $result;
}