我想在使用Symfony2.8和Doctrine 2.5时，在Doctrine ORM查询中过滤掉所有集合包含恰好3个元素的数据集。
$em = $this->getDoctrine()->getManager();
$query = $em->getRepository("AppBundle:EduStructItem")
->createQueryBuilder('e')
->addSelect('COUNT(e.preconditions) AS HIDDEN numberpre')
->having('numberpre = 3')
->getQuery();
$res = $query->getResult();
dump($res);
foreach ($res as $entity){
print "title:".$entity->getTitle()."<br>";
dump($entity->getPreconditions()->toArray());
}
preconditions是一个包含前提条件集合的数组集合。
最终，我想要获取所有恰好有3个前提条件的结果。此外，按照数组集合中值的数量排序也会很棒（类似于order by Count(e.preconditions)）。
由于使用了另一个bundle，我从2.5.2版本降级到了2.5.0版本。虽然我不认为这是问题的原因，但为了完整起见，这里是我composer Show命令中Doctrine部分的内容:
data-dog/pager-bundle v0.2.4 Paginator bundle for symfony2 and doctrine orm, allows customization with filters and sorters
doctrine/annotations v1.2.7 Docblock Annotations Parser
doctrine/cache v1.5.2 Caching library offering an object-oriented API for many cache backends
doctrine/collections v1.3.0 Collections Abstraction library
doctrine/common v2.5.2 Common Library for Doctrine projects
doctrine/data-fixtures v1.1.1 Data Fixtures for all Doctrine Object Managers
doctrine/dbal v2.5.2 Database Abstraction Layer
doctrine/doctrine-bundle 1.6.1 Symfony DoctrineBundle
doctrine/doctrine-cache-bundle 1.2.2 Symfony Bundle for Doctrine Cache
doctrine/doctrine-fixtures-bundle 2.3.0 Symfony DoctrineFixturesBundle
doctrine/doctrine-migrations-bundle 1.1.1 Symfony DoctrineMigrationsBundle
doctrine/inflector v1.1.0 Common String Manipulations with regard to casing and singular/plural rules.
doctrine/instantiator 1.0.5 A small, lightweight utility to instantiate objects in PHP without invoking their constructors
doctrine/lexer v1.0.1 Base library for a lexer that can be used in Top-Down, Recursive Descent Parsers.
doctrine/migrations v1.1.0 Database Schema migrations using Doctrine DBAL
doctrine/orm v2.5.0 Object-Relational-Mapper for PHP
这是一个测试实体：
<?php
// src/AppBundle/Entity/EduStructItem.php
namespace AppBundle\Entity;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Validator\Constraints as Assert;
/**
* @ORM\Entity
* @ORM\Table(name="test_edustructitemcollection")
*/
class EduStructItem
{
/**
* @ORM\Column(type="integer")
* @ORM\Id
* @ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
* @var string
* @Assert\NotBlank()
* @ORM\Column(type="string", length=255, nullable=false)
*/
private $title;
/**
* Preconditions are EduStructItems referencing to an EduStructItem.
* For a single EduStructItem its empty (which have no subelements).
* A join table holds the references of a main EduStructItem to its sub-EduStructItems (preconditions)
*
* @ORM\ManyToMany(targetEntity="EduStructItem",indexBy="id", cascade={"persist"})
* @ORM\JoinTable(name="test_edustructitem_preconditioncollection",
* joinColumns={@ORM\JoinColumn(name="edustructitem_id", referencedColumnName="id")},
* inverseJoinColumns={@ORM\JoinColumn(name="edustructitem_precondition_id", referencedColumnName="id")}
* )
*/
public $preconditions;
public function __construct()
{
$this->preconditions = new ArrayCollection();
}
public function getTitle()
{
return $this->title;
}
public function setTitle($title)
{
$this->title = $title;
}
public function getPreconditions()
{
return $this->preconditions;
}
public function addPrecondition(\AppBundle\Entity\EduStructItem $precondition)
{
$this->preconditions->add($precondition);
}
public function removePrecondition(\AppBundle\Entity\EduStructItem $precondition)
{
$this->preconditions->removeElement($precondition);
}
}
?>
最后我总是遇到错误: [语义错误]第0行，第18列处'preconditions)'附近：错误：无效的PathExpression。应该使用StateFieldPathExpression或SingleValuedAssociationField。
现在我尝试了你的新解决方案:
$em = $this->getDoctrine()->getManager();
$query = $em->getRepository("AppBundle:EduStructItem")
->createQueryBuilder('e')
->addSelect('COUNT(e.preconditions) AS HIDDEN countpre')
->join('e.preconditions', 'precondition', Join::WITH)
->having('countpre = 1')
->getQuery();
并再次收到错误提示：[语义错误]第0行，第18列附近的'preconditions)'：错误：无效的PathExpression。需要StateFieldPathExpression或SingleValuedAssociationField。如果我在HIDDEN之前写别名，我也会得到以下错误提示：[语义错误]第0行，第53列附近的'FROM AppBundle\Entity\EduStructItem'：错误：未定义类'FROM'。请注意，这是一个自反关系，并且只有一个实体，但是有两个表格。正如您可以在我的实体注释中看到的那样，自关系保存在test_edustructitem_preconditioncollection表中，该表由Doctrine根据注释生成。我尝试了您最新的解决方案：
$qb = $em->getRepository("AppBundle:EduStructItem")
->createQueryBuilder('item');
$qb->addSelect('COUNT(precondition.id) AS countpre HIDDEN ')
->join('item.preconditions', 'precondition', Join::WITH)
->having('countpre = 1');
当我在HIDDEN之前使用countpre时，我总是会遇到以下错误： [语义错误] 第0行，第56列附近的'FROM AppBundle\Entity\EduStructItem'：错误：未定义类'FROM'。
但是当我将countpre放在HIDDEN之后时：
$qb = $em->getRepository("AppBundle:EduStructItem")
->createQueryBuilder('item');
$qb->addSelect('COUNT(precondition.id) AS HIDDEN countpre')
->join('item.preconditions', 'precondition', Join::WITH)
->having('countpre = 1');
我遇到了错误： 执行'SELECT t0_.id AS id_0, t0_.title AS title_1, COUNT(t1_.id) AS sclr_2 FROM test_edustructitemcollection t0_ INNER JOIN test_edustructitem_preconditioncollection t2_ ON t0_.id = t2_.edustructitem_id INNER JOIN test_edustructitemcollection t1_ ON t1_.id = t2_.edustructitem_precondition_id HAVING sclr_2 = 1'时出现异常: SQLSTATE [42S22, 207]: [Microsoft][ODBC Driver 11 for SQL Server][SQL Server]Ungültiger Spaltenname 'sclr_2'. 500 Internal Server Error - DBALException 1个相关的异常: SQLSrvException » 请注意，只有一个实体具有自引用，而且有这两个表：
USE [easylearndev4_rsc]
GO
/****** Object: Table [dbo].[test_edustructitemcollection] Script Date: 14.12.2015 09:31:55 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[test_edustructitemcollection](
[id] [int] IDENTITY(1,1) NOT NULL,
[title] [nvarchar](255) NOT NULL,
PRIMARY KEY CLUSTERED
(
[id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
并且。
USE [easylearndev4_rsc]
GO
/****** Object: Table [dbo].[test_edustructitem_preconditioncollection] Script Date: 14.12.2015 09:32:21 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
REATE TABLE [dbo].[test_edustructitem_preconditioncollection](
[edustructitem_id] [int] NOT NULL,
[edustructitem_precondition_id] [int] NOT NULL,
PRIMARY KEY CLUSTERED
(
[edustructitem_id] ASC,
[edustructitem_precondition_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[test_edustructitem_preconditioncollection] WITH CHECK ADD CONSTRAINT [FK_34E716A81B7A6CEB] FOREIGN KEY([edustructitem_precondition_id])
REFERENCES [dbo].[test_edustructitemcollection] ([id])
GO
ALTER TABLE [dbo].[test_edustructitem_preconditioncollection] CHECK CONSTRAINT [FK_34E716A81B7A6CEB]
GO
ALTER TABLE [dbo].[test_edustructitem_preconditioncollection] WITH CHECK ADD CONSTRAINT [FK_34E716A85D864668] FOREIGN KEY([edustructitem_id])
REFERENCES [dbo].[test_edustructitemcollection] ([id])
GO
ALTER TABLE [dbo].[test_edustructitem_preconditioncollection] CHECK CONSTRAINT [FK_34E716A85D864668]
GO
最后，我自己找到了一种解决方法：
$em = $this->getDoctrine()->getManager();
$qb = $em->getRepository("AppBundle:EduStructItem")
->createQueryBuilder('e');
$qb->join('e.preconditions', 'p', Join::WITH)
->groupBy('e.id, e.title')
->having('count(p.id) = 1');
但我对此并不满意，因为ArrayCollection已经是聚合数据，为什么还要再次进行连接、计数和分组！这不应该是Doctrine的想法吧！有没有人知道更好的解决方案？