symfony - Symfony 2 和 Doctrine 2 - 使用“fetch”连接返回空数组

Question

我有一个带有 yml 映射的实体“BlogPosts”：

type: entity
table: blog_posts
id:
  id:
    type: integer
    generator: { strategy: AUTO }
fields:
  body:
    type: text
  created_at:
    type: datetime
manyToMany:
  replies:
    targetEntity: BlogPosts
    inversedBy: replyTo
    orderBy: {"id": "DESC"}
    orphanRemoval: true
    joinTable:
      name: blog_post_replies
      joinColumns:
        reply_to_id:
          referencedColumnName: id
      inverseJoinColumns:
        reply_id:
          referencedColumnName: id
  replyTo:
    targetEntity: BlogPosts
    mappedBy: replies
manyToOne:
  user:
    targetEntity: User
    inversedBy: posts
    joinColumns:
      user_id:
        referencedColumnName: id
        nullable: false

问题是，当我尝试使用 JOIN 获取数据时，结果为空。

    $query = $em->createQuery("SELECT p, rl FROM <Bundle>:BlogPosts p JOIN p.replies rl WHERE p.user = 1");
    $posts = $query->getResult(); // Returns empty array

但它在没有连接的情况下完美运行：

    $query = $em->createQuery("SELECT p FROM <Bundle>:BlogPosts p WHERE p.user = 1");
    $posts = $query->getResult(); // Works as intended

我错过了什么？我真的很绝望:(

编辑：刚刚发现，它只返回有回复的帖子。我如何选择所有帖子，如果有回复，也回复？

Answer 1

所以我发现了问题！而不是 JOIN 我使用了 LEFT JOIN：

$query = $em->createQuery("SELECT p, rl FROM <Bundle>:BlogPosts p LEFT JOIN p.replies rl WHERE p.user = 1");
$posts = $query->getResult(); // Now it works like a charm!

所以现在 MySQL 将结果加入到博客文章中！使用简单的 JOIN 时，它会尝试将帖子加入回复中，如果帖子没有，则结果将为空！