学说：急于加载一个懒惰的关系的关系？

Question

我正在使用Doctrine 2来映射学术计划。这里有一个简单看关系：

• 一个类有事件（一到多）
  • 的事件有型（多到一）
  • 一种事件具有位置（多到一个）

使用$em->find()我只能使用惰性加载关系获取类。或者在连接中使用DQL，我可以加载整个对象图。中间是否有解决方案？

我想偷懒加载关系去取类，然后在一定条件下触发事件关系的渴望负荷和所有事件性能。所以，当我打电话像$class->getEventsHydrateAll()，所有事件和事件类型和事件地点将被立即水合。

我想我可以通过更新我的事件架构标志型和位置关系，因为fetch="EAGER"做到这一点。但是我想要控制这种深度水合作用发生的时间。

这里有一个尝试我在类资源库做了，但原则是运行单个查询查找每个型和位置。

$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; 
} 

有没有人知道是否Doctrine支持这个？谢谢！

Answer 1

我不确定，但我认为getSingleResult会覆盖水合模式。

尝试“执行”来代替，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; DR：

您可以使用EAGER标志上的类属性有它加载它的关系热切。 http://doctrine-orm.readthedocs.org/en/latest/reference/annotations-reference.html#manytoone

我不确定这是否会对您有帮助，但这是我解决问题的方法。

首先介绍一下我的情况。我目前正在创建一个OAuth 2实现，我希望在该范围内对其进行细粒度控制。作用域非常精细（例如电子邮件地址，用户名等），然后您可以为它们分别设置各自的权限，以便读取，创建，编辑和删除。

下面是一个数据库图表松散表明关系：

所以我的问题是，如何我举个例子，看看如果一个特定的标记允许阅读（许可）一用户名（范围）？

如果我加载令牌，然后得到它的所有权限，那么的foreach 阅读允许，我检查了用户名范围，那么这是一个很大的数据库访问。

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的这大部分是收集连接到的权限范围。我们可以用渴望标志的关系从权限范围与权限抢范围：

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

注意fetch="EAGER"旗ManyToOne注释。

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