Doctrine2通过QueryBuilder获取manyToMany关联的行 | ine2通过QueryBuilder获取manyToMany关联

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问题描述

大家。
我有2个实体城市和POI。 Mapping如下所示：

everyone.I have 2 entities City and POI. Mapping looks like this:

class City {
/**
 * @ORM\ManyToMany(targetEntity="POI", mappedBy="cities")
 * @ORM\OrderBy({"position" = "ASC"})
 */
protected $pois;

和

class POI {
/**
 * @ORM\ManyToMany(targetEntity="City", inversedBy="pois")
 * @ORM\JoinTable(name="poi_cities")
 */
protected $cities;

我想使用QueryBuilder获取与某个城市至少有1个关联的所有POI。我应该可以使用exists（）函数，但是我不安静知道如何。

I would like to fetch all POIs that have at least 1 association with some City using QueryBuilder. I should probably use exists() function but I don't quiet know how.

推荐答案

你必须左加入，并检查城市是否为空。

You'd have to Left join them and check if cities is null.

$qb->select('p', 'c')
   ->from('AcmeDemoBundle:POI', 'p')
   ->leftJoin('p.cities', 'c')
   ->where('c IS NOT NULL');

我没有测试过，但我希望它给你一般的方向。您可以从。

I haven't tested it, but I hope it gives you the general direction. You can read more about the QueryBuilder from here.

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