动态加载与 Doctrine 的深层关系

Question

我目前正在使用以下堆栈开发 API；

• Symfony (3)
• FOSRestBundle
• 分形

我想集成通过查询参数指定检索实体/集合时要包含哪些关系的功能，例如；

[GET] /users?include=friends.addresses

Fractal comes with the ability to handle includes 然而，由于这发生在响应构建的序列化点附近，每个相关实体都通过延迟加载检索，从而触发额外的查询。

有没有办法告诉 Doctrine 在检索集合时也动态检索指定的关系？我见过the following from the Doctrine docs which shows how to dynamically change the fetch mode，但这似乎只适用于目标实体上的关联（上例中的friends）而不是更深层次的关系（示例中的friends 中的addresses）。

谢谢！

Answer 1

如果我没记错的话，你可以通过加入它们来“预加载”关系，而不是让延迟加载机制来处理它。一个想法可能是创建一个根据您的条件创建查询构建器的服务。这是我的意思的粗略的sn-p：

class EagerService
{
    protected $em;

    public function __construct(EntityManager $em)
    {
        $this->em = $em;
    }

    public function resolveIncludes($class, $alias, $includes) 
    {
        // Parse includes into an array
        if (strpos($includes, '.') !== false) {
            $relations = explode('.', $includes);
        } else {
            $relations = [$includes];
        }

        // The next relation is owned by the previous one, so we keep track of the previous relation
        $previousRelation = $alias;
        $qb = $em->getRepository($class)->getQueryBuilder($previousRelation);
        foreach ($relations as $relation) {
            // Add inner joins to the query builder referencing the new relation
            $qb->innerJoin("{$previousRelation}.{$relation}", $relation);
            $previousRelation = $relation;
        }

        // Return query builder or the result of the query
        return $qb;
    }
}