Symfony2的__toString（）错误

Question

我有保存实体回我这个错误的一个问题：

Catchable Fatal Error: Method My\BusinessBundle\Entity\Type::__toString() 
must return a string value in 
/var/www/MyBusiness0_1/vendor/doctrine/orm/lib/Doctrine/ORM/ORMInvalidArgumentException.php line 113 

奇怪的是，该方法__的toString（）是实体型！

class Type 
{ 
//.. 

/** 
* @var string 
* 
* @ORM\Column(name="type", type="string", length=100) 
*/ 
private $type; 

/** 
* @ORM\OneToMany(targetEntity="MailTelCont", mappedBy="type") 
*/ 
protected $mailTelContacts; 

public function __construct() 
{ 
    $this->mailTelContacts = new \Doctrine\Common\Collections\ArrayCollection(); 
} 

public function __toString() 
{ 
    return $this->getType(); 
} 
//... 

另一个奇怪的事情是，如果我把级联= {“坚持”}类MailTelCont上多对一的关系“型”不显示我这个错误，但在保存类型的新领域..

类MailTelCont

class MailTelCont 
{ 
//.. 
/** 
* @var string 
* 
* @ORM\Column(name="contact", type="string", length=100) 
*/ 
private $contact; 

/** 
* @ORM\ManyToOne(targetEntity="Type", inversedBy="mailTelContacts") 
* @ORM\JoinColumn(name="type_id", referencedColumnName="id") 
*/ 
private $type; 

/** 
* @ORM\ManyToOne(targetEntity="Anagrafica", inversedBy="mailTelContacts", cascade={"persist"}) 
* @ORM\JoinColumn(name="anagrafica_id", referencedColumnName="id") 
* @Assert\Type(type="My\BusinessBundle\Entity\Anagrafica") 
*/ 
private $anagrafica; 

public function __toString() 
{ 
    return $this->getContact(); 
} 

呼叫以这种方式嵌套 “AnagraficType” 的形式：

class TypeType extends AbstractType 
{ 
public function buildForm(FormBuilderInterface $builder, array $options) 
{ 
    $builder 
     ->add('type', 'entity', array(
       'class' => 'My\BusinessBundle\Entity\Type', 
       'attr' => array('class' => 'conct'), 
       'property' => 'type', 
       'label' => 'Tipologia', 
     )) 
    ; 
} 
***** 
class MailTelContType extends AbstractType 
{ 
public function buildForm(FormBuilderInterface $builder, array $options) 
{ 
    $builder 
     ->add('type', new TypeType()) 
     ->add('contact', 'text', array('label' => 'Contatto'))     
    ; 
} 
***** 
class AnagraficaType extends AbstractType 
{ 
public function buildForm(FormBuilderInterface $builder, array $options) 
{ 
    $builder->add('mailTelContacts', 'collection', array('type' => new MailTelContType(), 
       'allow_add' => true, 
       'allow_delete' => true, 
       'prototype' => true, 
       'by_reference' => false 
      )) 

我在哪里做错了？

Answer 1

我认为那些值是null然后。你尝试：

public function __toString() 
{ 
    return (string) $this->getType(); 
} 

和

public function __toString() 
{ 
    return (string) $this->getContact(); 
} 

当值null将被强制转换为字符串，你不应该得到这个异常的方式。