（Doctrine）选择数组集合不为空的位置？

Question

我有一个班级帖子：

/**
 * @ORM\Entity(repositoryClass="App\Repository\PostRepository")
 */
class Post
{
    const TYPE_TEXT   = 1;
    const TYPE_PHOTOS = 2;
    const TYPE_VIDEO  = 3;

    /**
     * @ORM\OneToMany(targetEntity="Photo", mappedBy="post")
     */
    private $photos;

    and other properties, methods, etc... 

我想只带回有照片的帖子。

我有一个DQL查询，如：

    $qb = $this->createQueryBuilder('p');
    $qb->select('p, postPhotos, etc...')
        ->leftJoin('p.photos', 'postPhotos')
        ->leftJoin('p.videos', 'postVideos')
        etc...

    if ($mediaType != null)
    {
        switch ($mediaType) {
            case Post::TYPE_PHOTOS:
                $qb->andWhere('postPhotos != :null')
                    ->setParameter('null', null);

“！=：null”不起作用，COUNT（postPhotos）也不起作用（显然是出于聚合的原因）。

有没有办法可以指定只带回一张或多张照片的帖子？

Answer 1

快速回答：如果你用加入（或内部加入）取代你对左连接的使用，那么你将得到你想要的：只有至少有1张照片的帖子。

细节

如果您看一下这个有用的问答：

Different MySQL Join Methods

...你会发现一些优秀的维恩图，显示了左连接和内连接之间的区别。然后，如果您查看Doctrine的Doctrine \ ORM \ QueryBuilder类，您会发现它们有三种连接方法：

• join（只调用内部Join）
• 内部联接
• 离开加入

    /**
     * Creates and adds a join over an entity association to the query.
     *
     * The entities in the joined association will be fetched as part of the query
     * result if the alias used for the joined association is placed in the select
     * expressions.
     *
     * <code>
     *     $qb = $em->createQueryBuilder()
     *         ->select('u')
     *         ->from('User', 'u')
     *         ->join('u.Phonenumbers', 'p', Expr\Join::WITH, 'p.is_primary = 1');
     * </code>
     *
     * @param string      $join          The relationship to join.
     * @param string      $alias         The alias of the join.
     * @param string|null $conditionType The condition type constant. Either ON or WITH.
     * @param string|null $condition     The condition for the join.
     * @param string|null $indexBy       The index for the join.
     *
     * @return self
     */
    public function join($join, $alias, $conditionType = null, $condition = null, $indexBy = null)
    {
        return $this->innerJoin($join, $alias, $conditionType, $condition, $indexBy);
    }

    /**
     * Creates and adds a join over an entity association to the query.
     *
     * The entities in the joined association will be fetched as part of the query
     * result if the alias used for the joined association is placed in the select
     * expressions.
     *
     *     [php]
     *     $qb = $em->createQueryBuilder()
     *         ->select('u')
     *         ->from('User', 'u')
     *         ->innerJoin('u.Phonenumbers', 'p', Expr\Join::WITH, 'p.is_primary = 1');
     *
     * @param string      $join          The relationship to join.
     * @param string      $alias         The alias of the join.
     * @param string|null $conditionType The condition type constant. Either ON or WITH.
     * @param string|null $condition     The condition for the join.
     * @param string|null $indexBy       The index for the join.
     *
     * @return self
     */
    public function innerJoin($join, $alias, $conditionType = null, $condition = null, $indexBy = null)
    {
        $parentAlias = substr($join, 0, strpos($join, '.'));

        $rootAlias = $this->findRootAlias($alias, $parentAlias);

        $join = new Expr\Join(
            Expr\Join::INNER_JOIN, $join, $alias, $conditionType, $condition, $indexBy
        );

        return $this->add('join', [$rootAlias => $join], true);
    }

    /**
     * Creates and adds a left join over an entity association to the query.
     *
     * The entities in the joined association will be fetched as part of the query
     * result if the alias used for the joined association is placed in the select
     * expressions.
     *
     * <code>
     *     $qb = $em->createQueryBuilder()
     *         ->select('u')
     *         ->from('User', 'u')
     *         ->leftJoin('u.Phonenumbers', 'p', Expr\Join::WITH, 'p.is_primary = 1');
     * </code>
     *
     * @param string      $join          The relationship to join.
     * @param string      $alias         The alias of the join.
     * @param string|null $conditionType The condition type constant. Either ON or WITH.
     * @param string|null $condition     The condition for the join.
     * @param string|null $indexBy       The index for the join.
     *
     * @return self
     */
    public function leftJoin($join, $alias, $conditionType = null, $condition = null, $indexBy = null)
    {
        $parentAlias = substr($join, 0, strpos($join, '.'));

        $rootAlias = $this->findRootAlias($alias, $parentAlias);

        $join = new Expr\Join(
            Expr\Join::LEFT_JOIN, $join, $alias, $conditionType, $condition, $indexBy
        );

        return $this->add('join', [$rootAlias => $join], true);
    }

更改代码以使用innerJoin（或只是加入）将导致Doctrine在生成的SQL中发出INNER JOIN，这将只返回连接两侧存在“something”的记录，因此，任何没有Photos的帖子都不会被包括在结果中。