教义：渴望加载懒惰关系的关系？

Question

我正在使用教义2来绘制学术时间表。以下是对这些关系的简化观察：

• 一个类有事件（一对多）
  • 事件具有类型（多对一）
  • 一个事件有一个位置（多对一）

  使用$em-

  我想获取一个具有懒惰加载关系的类，然后在特定条件下触发事件关系和所有事件属性的急切加载。所以当我把类似$class这样的东西叫做

  我想我可以通过更新事件模式来实现这一点，将类型和位置关系标记为fetch=“EAGER”。但我想控制这种深层水合作用何时发生。

  这是我在类存储库中所做的一次尝试，但Doctrine正在运行单独的查询来查找每个类型和位置。

  $query = $this->_em->createQuery('
          SELECT c FROM My\Entity\Class c
          WHERE c.id = :classId
  ');
  $query->setParameter('classId', $classId)
        ->setFetchMode('My\Entity\Event', 'type', 'EAGER')
        ->setFetchMode('My\Entity\Event', 'location', 'EAGER');
  
  try {
      return $query->getSingleResult();
  } catch (\Doctrine\ORM\NoResultException $e) {
      return NULL;
  }
  

  有人知道教义是否支持这一点吗？谢谢！




Answer 1

我不确定，但我认为getSingleResult会覆盖水合模式。

尝试"执行"，如本例所示：http://docs.doctrine-project.org/en/latest/reference/dql-doctrine-query-language.html#dql-temporarily-change-fetch-mode

Answer 2

TL；博士：

您可以在类属性上使用EAGER标志来急切地加载它的关系。http://doctrine-orm.readthedocs.org/en/latest/reference/annotations-reference.html#manytoone

我不确定这是否对你有帮助，但我就是这样解决的。

首先介绍一下我的背景。我目前正在创建一个OAuth 2实现，我希望对范围进行精细的粒度控制。范围非常细粒度（例如电子邮件、用户名等），然后您可以对每个范围设置读取、创建、编辑和删除的单独权限。

下面是一个数据库图表，松散地显示了这种关系：

因此，我的问题是，例如，如何查看特定令牌是否允许读取（权限）用户名（范围）？

如果我加载令牌，然后获得它的所有权限，然后获得读取权限，我检查用户名范围，那么这是大量的数据库访问。

测试代码：

$permissions = $this->getOAuthHelper()
                    ->getAccessToken($accessToken)
                    ->getPermissions();
$results = [];
foreach ($permissions as $permission) {
    $results[] = $permission->getScope()->getTitle();
}
return $results;

查询日志：

150630 10:49:47    54 Connect   root@localhost on api
150630 10:49:51    54 Query     SELECT t0.id AS id1, t0.token AS token2, t0.token_expiration AS token_expiration3, t0.refresh AS refresh4, t0.created_at AS created_at5, t0.deleted_at AS deleted_at6, t0.user_id AS user_id7, t0.client_id AS client_id8 FROM oauth_access_tokens t0 WHERE t0.token = 'user-test-token' LIMIT 1
                   54 Query     SELECT t0.id AS id1, t0.access_permission AS access_permission2, t0.scope_id AS scope_id3 FROM oauth_permissions t0 INNER JOIN oauth_access_to_permissions ON t0.id = oauth_access_to_permissions.permission_id WHERE oauth_access_to_permissions.access_id = '1'
150630 10:49:52    54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '1'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '2'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '3'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '4'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '5'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '6'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '7'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '8'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '9'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '10'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '11'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '12'
                   54 Query     SELECT t0.id AS id1, t0.title AS title2, t0.brief AS brief3, t0.category_id AS category_id4 FROM oauth_scopes t0 WHERE t0.id = '13'
                   54 Quit

但是，我们可以在这里看到，大部分内容是收集附加到权限的作用域。我们可以在从权限到范围的关系上使用“渴望”标志来获取具有以下权限的范围：

/**
 * @var Scope
 *
 * @ORM\ManyToOne(targetEntity="OAuthScope", fetch="EAGER")
 * @ORM\JoinColumns({
 *   @ORM\JoinColumn(name="scope_id", referencedColumnName="id")
 * })
 */
protected $scope;

注意manytone注释上的fetch=“EAGER”标志。

现在，如果我们运行完全相同的代码：

150630 11:00:06    55 Connect   root@localhost on api
150630 11:00:10    55 Query     SELECT t0.id AS id1, t0.token AS token2, t0.token_expiration AS token_expiration3, t0.refresh AS refresh4, t0.created_at AS created_at5, t0.deleted_at AS deleted_at6, t0.user_id AS user_id7, t0.client_id AS client_id8 FROM oauth_access_tokens t0 WHERE t0.token = 'user-test-token' LIMIT 1
150630 11:00:11    55 Query     SELECT t0.id AS id1, t0.access_permission AS access_permission2, t0.scope_id AS scope_id3, t4.id AS id5, t4.title AS title6, t4.brief AS brief7, t4.category_id AS category_id8 FROM oauth_permissions t0 LEFT JOIN oauth_scopes t4 ON t0.scope_id = t4.id INNER JOIN oauth_access_to_permissions ON t0.id = oauth_access_to_permissions.permission_id WHERE oauth_access_to_permissions.access_id = '1'
                   55 Quit