由于我最后一个问题的答案，我能够减少 SELECT -查询在第一层。不幸的是，关联实体的链接更深，例如:
Item -> Group -> Subscriber -> User -> username
// ItemRepository
public function findAll() {
return $this->createQueryBuilder('item')
->addSelect('groups')->join('item.groups', 'groups')
->getQuery()->getResult()
}
{% for item in items %}
{# Level: 0 #}
Name: {{ item.name }}<br/>
Groups:<br/>
<ul>
{# Level: 1 #}
{% for group in item.groups %}
<li>{{ group.name }}<br/>
<ol>
{# Level: 2 #}
{% for subscriber in group.subscribers %}
{# Level: 3 #}
<li>{{ subscriber.user.username }}</li>
{% endfor %}
</ol>
</li>
{% endfor %}
</ul>
{% endfor %}
注意:我使用jsonSerialize来准备JSON-data，其中也包括多级迭代。
use JsonSerializable;
// ...
class Item implements JsonSerializable {
// ...
public function jsonSerialize() {
$subscribers = array();
$groups = $this->getGroups();
foreach ($groups as $group) {
foreach ($group->getSubscribers() as $subscriber) {
$subscribers[$subscriber->getId()] = array(
'userId' => $subscriber->getUser()->getId();
'username' => $subscriber->getUser()->getUsername();
);
}
}
return array(
'id' => $this->getId(),
'subscribers' => $subscribers
// ...
);
}
}
是否有一种方法来加入更深的关联数据以及减少 SELECT -查询再次(for twig和jsonSerialize())?
我建议您在特定查询中更改获取模式，如文档中所述。
所以你可以这样描述你的查询:
$qb = $this->createQueryBuilder('item')
->addSelect('groups')->join('item.groups', 'groups'); // Not necessary anymore
$query = $qb->getQuery();
// Describe here all the entity and the association name that you want to fetch eager
$query->setFetchMode("YourBundle''Entity''Item", "groups", ClassMetadata::FETCH_EAGER);
$query->setFetchMode("YourBundle''Entity''Groups", "subscriber", ClassMetadata::FETCH_EAGER);
$query->setFetchMode("YourBundle''Entity''Subscriber", "user", ClassMetadata::FETCH_EAGER);
...
return $qb->->getResult();
注:
在查询期间更改读取模式只能用于一对一和多对一关系
希望对您有所帮助