Fetching Related Objects exception when work with mutil database - symfony

Question

when i use mutil database with doctrine to related objects ,it can't find the table in the right way.
ta is table name ,in the acc database.
tb is table name too,in the trade database.
ta record:
id name
1 ta名称
tb record:
id name
1 tb名称
$em=$this->getDoctrine()->getRepository(ta::class,'customer');
$ta=$em->find(2);//now ,it can fetch the data,and the data is right
$tb=$ta->getTbTable();
$szName=$tb->getName(); //i want to get the tb record,it will throw an exception :
...................................
'acc.tb' doesn't exist"
actully,tb is in the trade database.
how to fix these problem
<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\ORM\Mapping\PrePersist;
use Doctrine\ORM\Mapping\PreUpdate;
use Doctrine\ORM\Mapping\HasLifecycleCallbacks;
use Symfony\Component\Validator\Constraints as Assert;
/**
* #ORM\Table(name="ta")
* #ORM\Entity(repositoryClass = "AppBundle\Entity\taRepository")
* #ORM\HasLifecycleCallbacks()
* #package AppBundle\Entity
*/
class ta {
/**
* #ORM\Column(type="integer",unique=true)
* #Assert\NotBlank(message="账号ID不能为空")
* #ORM\Id
*/
private $id;
/**
* #ORM\Column(type="string")
*/
private $name;
/**
* #ORM\ManyToOne(targetEntity="AppBundle\EntityTrade\tb")
* #ORM\JoinColumn(name="id",referencedColumnName="id")
*/
private $tb_table;
/**
* Set id.
*
* #param int $id
*
* #return ta
*/
public function setId($id)
{
$this->id = $id;
return $this;
}
/**
* Get id.
*
* #return int
*/
public function getId()
{
return $this->id;
}
/**
* Set name.
*
* #param string $name
*
* #return ta
*/
public function setName($name)
{
$this->name = $name;
return $this;
}
/**
* Get name.
*
* #return string
*/
public function getName()
{
return $this->name;
}
/**
* Set tbTable.
*
* #param \AppBundle\EntityTrade\tb|null $tbTable
*
* #return ta
*/
public function setTbTable(\AppBundle\EntityTrade\tb $tbTable = null)
{
$this->tb_table = $tbTable;
return $this;
}
/**
* Get tbTable.
*
* #return \AppBundle\EntityTrade\tb|null
*/
public function getTbTable()
{
return $this->tb_table;
}
}
<?php
namespace AppBundle\EntityTrade;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\ORM\Mapping\PrePersist;
use Doctrine\ORM\Mapping\PreUpdate;
use Doctrine\ORM\Mapping\HasLifecycleCallbacks;
use Symfony\Component\Validator\Constraints as Assert;
/**
* #ORM\Table(name="tb")
* #ORM\Entity(repositoryClass = "AppBundle\EntityTrade\tbRepository")
* #ORM\HasLifecycleCallbacks()
* #package AppBundle\EntityTrade
*/
class tb {
/**
* #ORM\Column(type="integer",unique=true)
* #Assert\NotBlank(message="账号ID不能为空")
* #ORM\Id
*/
private $id;
/**
* #ORM\Column(type="string")
*/
private $name;
/**
* Set id.
*
* #param int $id
*
* #return tb
*/
public function setId($id)
{
$this->id = $id;
return $this;
}
/**
* Get id.
*
* #return int
*/
public function getId()
{
return $this->id;
}
/**
* Set name.
*
* #param string $name
*
* #return tb
*/
public function setName($name)
{
$this->name = $name;
return $this;
}
/**
* Get name.
*
* #return string
*/
public function getName()
{
return $this->name;
}
}
class defaultController{
public function indexAction(){
$em=$this->getDoctrine()->getRepository(ta::class,'customer');
$ta=$em->find(2);
$tb=$ta->getTbTable();
$szName=$tb->getName();
}
}

Answer 1

It will not work in this way. Doctrine's EntityManager only support management of entities within single database, so your cross-database relation between ta and tb will not be established. Please refer this issue in Doctrine bug tracker for more information.
However your goal can be accomplished into slightly different way. You can't establish cross-database relations between entities, but you can, of course, store ids that refers entities into different databases. Hence you can move all cross-database relations logic into repositories. For example let's assume that you have 2 EntityManager for each database: $accEm for acc database and $tradeEm for trade database. Taking in mind that you're using Symfony - they can be configured into DoctrineBundle configuration and then injected into services.
You will need to create some changes into your code:
ta.php, I've omitted most of code to express changes that needs to be made.
namespace AppBundle\Entity;
class ta
{
/**
* #ORM\Column(type="integer", nullable=true)
* #var int
*/
private $tb_table; // Notice that it is not a reference anymore, but simple integer
/**
* Set tbTable.
*
* #param \AppBundle\EntityTrade\tb|null $tbTable
*
* #return ta
*/
public function setTbTable(\AppBundle\EntityTrade\tb $tbTable = null)
{
// You can also consider updating this method to accept plain integers aswel
$this->tb_table = $tbTable instanceof \AppBundle\EntityTrade\tb ? $tbTable->getId() : null;
return $this;
}
/**
* Get tbTable.
*
* #return int|null
*/
public function getTbTable()
{
// Also notice that plain integer is returned, you may want to rename column and method names to reflect this change of column meaning
return $this->tb_table;
}
}
taRepository.php, I've also omitted most of code that can be there
namespace AppBundle\Entity;
use Doctrine\ORM\EntityManager;
use Doctrine\ORM\EntityRepository;
class taRepository extends EntityRepository {
/**
* #var EntityManager
*/
private $tradeEm;
/**
* #param EntityManager $tradeEm
*/
public function setTradeEntityManader(EntityManager $tradeEm)
{
// It is required to pass instance of EntityManager for "trade" database here. It should be done via Symfony services configuration, please refer Symfony documentation on this topic if needed
$this->tradeEm = $tradeEm;
}
/**
* #param ta $ta
* #return \AppBundle\EntityTrade\tb|null
*/
public function getTbTable(ta $ta) {
// This method should be used instead of $ta::getTbTable()
$tbId = $ta->getTbTable();
if ($tbId === null) {
return null;
}
return $this->tradeEm->find(\AppBundle\EntityTrade\tb::class, $tbId);
}
}
defaultController.php
namespace AppBundle\Controller;
use Doctrine\ORM\EntityManager;
class defaultController
{
/**
* #var EntityManager
*/
private $tradeEm;
/**
* #param EntityManager $tradeEm
*/
public function __construct(EntityManager $tradeEm)
{
// Same as before, this should be instance of EntityManager for "trade" database
$this->tradeEm = $tradeEm;
}
public function indexAction()
{
$em = $this->getDoctrine()->getRepository(ta::class, 'customer');
$ta = $em->find(2);
// Notice that we're not receiving "trade" database entity directly, but using corresponding EntityManager instead
$tb = $this->tradeEm->getTbTable($ta);
if ($tb !== null) {
$szName = $tb->getName();
}
}
}