Symfony和Doctrine使连接的查询起作用

Question

I've got an SQL query that returns all the rows in one table (country) which have a related entry in another table (ducks) but I'm struggling to turn this into DQL. This is a standard one-many relationship as each country can have multiple ducks, I believe it is all set up correctly as I can return ducks within a country and return the country a duck is in using standard code.

The working query is:

SELECT c.* FROM country c 
INNER JOIN ducks d 
ON c.id = d.country_id 
GROUP BY c.country 
ORDER BY c.country ASC

I've tried converting this to:

SELECT c FROM WfukDuckBundle:Country c 
INNER JOIN WfukDuckBundle:Ducks d 
ON c.id = d.country_id 
GROUP BY c.country 
ORDER BY c.country ASC

which produces the following error:

[Semantical Error] line 0, col 79 near 'd ON': Error: Identification Variable 
WfukDuckBundle:Ducks used in join path expression but was not defined before. 

I'm quite new to Symfony/Doctrine so I suspect it's probably something obvious!

I'm using Symfony 2.0.11 with doctrine

Update: I've Also tried:

SELECT c FROM WfukDuckBundle:Country c 
INNER JOIN c.ducks d 
ON c.id = d.country_id 
GROUP BY c.country 
ORDER BY c.country ASC

where 'ducks' is defined in the Country class as:

/**
 * @ORM\OneToMany(targetEntity="Ducks", mappedBy="country")
 */
protected $ducks;

public function __construct()
{
    $this->ducks = new ArrayCollection();
}

the definition for country in the ducks class is:

/**
* @ORM\ManyToOne(targetEntity="Country", inversedBy="ducks")
* @ORM\JoinColumn(name="country_id", referencedColumnName="id")
*/
private $country;

Answer 1

Do yourself a favour and use the query builder. Easier to read and update and reuse your queries

<?php

namespace Vendor\Prefix\Repository;

use Doctrine\ORM\EntityRepository;

class SomeRepository extends EntityRepository
{
    public function countryDucks()
    {
        // $em is the entity manager
        $qb = $em->createQueryBuilder();

        $qb
            ->select('country', 'duck')
            ->from('WfukDuckBundle:Country', 'country')
            ->innerJoin('country.ducks', 'duck')
            ->groupBy('country.country')
            ->orderBy('country.country', 'ASC')
        ;

        $query = $qb->getQuery();

        // Potential Hydration Modes
        // --------------------------------
        // Doctrine\ORM\Query::HYDRATE_OBJECT
        // Will give you an array of your object entities
        // --------------------------------
        // Doctrine\ORM\Query::HYDRATE_ARRAY 
        // Will give you an array mimicking 
        // your object graph 
        // --------------------------------

        return $query->getResult(\Doctrine\ORM\Query::HYDRATE_ARRAY);
    }
}