7.2 加载字段的例子
例子模块
我们将创建一个例子模块，加载一个节点（node），输出它的一些信息。
首先，至少创建一个节点，body 字段填写一些内容。
然后，我们创建这个模块，加载单一节点。
创建文件 field_example.info.yml（见代码1） ：
创建文件 field_example.routing.yml（见代码2）:
代码1：
name: Field Example
type: module
description: Example showing how to use fields
core: 8.x
package: Examples
代码2：
field_example.simple:
path: 'examples/field-example/simple'
defaults:
_controller: '\Drupal\field_example\Controller\FieldExampleDefaultController::simple'
requirements:
_access: 'TRUE'
创建控制器文件 src/Controller/FieldExampleDefaultController.php ：
<?php
/**
* @file
* Contains \Drupal\field_example\Controller\FieldExampleDefaultController.
*/
namespace Drupal\field_example\Controller;
use Drupal\Core\Controller\ControllerBase;
use Drupal\Core\Entity\EntityManagerInterface;
use Drupal\Core\Entity\Query\QueryFactory;
use Symfony\Component\DependencyInjection\ContainerInterface;
/**
* Controller routines for field example routes.
*/
class FieldExampleDefaultController extends ControllerBase {
/**
* @var \Drupal\Core\Entity\EntityManagerInterface
*/
protected $entityManager;
/**
* @var \Drupal\Core\Entity\Query\QueryFactory
*/
protected $queryFactory;
/**
* @param \Drupal\Core\Entity\EntityManagerInterface $entityManager
* @param \Drupal\Core\Entity\Query\QueryFactory $queryFactory
*/
public function __construct(EntityManagerInterface $entityManager, QueryFactory $queryFactory) {
$this->entityManager = $entityManager;
$this->queryFactory = $queryFactory;
}
/**
* @param \Symfony\Component\DependencyInjection\ContainerInterface $container
* @return static
*/
public static function create(ContainerInterface $container) {
return new static(
$container->get('entity.manager'),
$container->get('entity.query')
);
}
public function simple() {
/**
* We need to get one node with a body field.
*/
/**
* @var $query \Drupal\Core\Entity\Query\QueryInterface
*/
$query = $this->queryFactory->get('node');
// We just want some nodes.
$nids = $query->execute();
// If there are no nodes, we exit.
if (count($nids) < 1) {
return ['#markup' => $this->t('No nodes with a body field.')];
}
/**
* @var $entity_storage \Drupal\Core\Entity\ContentEntityStorageBase
*/
$entity_storage = $this->entityManager->getStorage('node');
/**
* @var $entity \Drupal\Core\Entity\Entity
*/
$entity = $entity_storage->load(array_values($nids)[0]);
// We will get the values from here.
return [
'#markup' => 'placeholder',
];
}
}
创建节点后，我们来取得 body 字段的值，并使用之前讲到的方式改变它。
/**
* @var $field \Drupal\Core\Field\FieldItemList
*/
$body_field = $entity->get('body');
// If we want a value off the first item, we can use a magic method __get()
// Which is sometimes easier to use.
$simple_value = $body_field->value;
// We get a array of items for this field.
// Unlike Drupal 7, there are no language keys.
$field_value = $body_field->getValue();
// We will set the summary to the value.
// We don't need to update the entity because the field setValue does that already.
$body_field->summary = $body_field->value;
// or
$field_value[0]['summary'] = $field_value[0]['value'];
$body_field->setValue($field_value);
/**
* @var $definition \Drupal\Core\Field\BaseFieldDefinition
*/
$definition = $body_field->getFieldDefinition();
$field_type = $definition->get('field_type');
return [
'field_type' => [
'#markup' => 'Field Type: ' . $field_type,
'#theme_wrappers' => [
'container' => [],
],
],
'field_value' => [
'#markup' => 'Field Value: ' . $body_field->value,
'#theme_wrappers' => [
'container' => [],
],
],
];