Symfony2 表单验证器 - 刷新前比较新旧值

Symfony 2.5 （http://symfony.com/doc/current/cookbook/validation/custom_constraint.html 的完整示例)

在此示例中，实体“NoDecreasingInteger”的字段“integerField”的新值必须高于存储的值。

创建约束：

// src/Acme/AcmeBundle/Validator/Constraints/IncrementOnly.php;
<?php
namespace Acme\AcmeBundle\Validator\Constraints;

use Symfony\Component\Validator\Constraint;

/**
 * @Annotation
 */
class IncrementOnly extends Constraint
{
  public $message = 'The new value %new% is least than the old %old%';

  public function getTargets()
  {
    return self::CLASS_CONSTRAINT;
  }

  public function validatedBy()
  {
    return 'increment_only';
  }
}

创建约束验证程序：

// src/Acme/AcmeBundle/Validator/Constraints/IncrementOnlyValidator.php
<?php
namespace Acme\AcmeBundle\Validator\Constraints;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

use Doctrine\ORM\EntityManager;

class IncrementOnlyValidator extends ConstraintValidator
{
  protected $em;

  public function __construct(EntityManager $em)
  {
    $this->em = $em;
  }

  public function validate($object, Constraint $constraint)
  {
    $new_value = $object->getIntegerField();

    $old_data = $this->em
      ->getUnitOfWork()
      ->getOriginalEntityData($object);

    // $old_data is empty if we create a new NoDecreasingInteger object.
    if (is_array($old_data) and !empty($old_data))
      {
        $old_value = $old_data['integerField'];

        if ($new_value < $old_value)
          {
            $this->context->buildViolation($constraint->message)
              ->setParameter("%new%", $new_value)
              ->setParameter('%old%', $old_value)
              ->addViolation();
          }
      }
  }
}

将验证程序绑定到实体：

// src/Acme/AcmeBundle/Resources/config/validator.yml
Acme\AcmeBundle\Entity\NoDecreasingInteger:
  constraints:
     - Acme\AcmeBundle\Validator\Constraints\IncrementOnly: ~

将 EntityManager 注入 IncrementOnlyValidator：

// src/Acme/AcmeBundle/Resources/config/services.yml
services:
   validator.increment_only:
        class: Acme\AcmeBundle\Validator\Constraints\IncrementOnlyValidator
        arguments: ["@doctrine.orm.entity_manager"]
        tags:
            - { name: validator.constraint_validator, alias: increment_only }

在 symfony2 中的自定义验证器中访问 EntityManager

您可以在控制器操作中检查以前的值...但这不会是一个干净的解决方案！

正常的表单验证将仅访问绑定到表单的数据...默认情况下无法访问“以前”的数据。

您尝试使用的回调约束无权访问容器或任何其他服务...因此，您无法轻松访问实体管理器（或任何以前的数据提供程序）来检查以前的值。

您需要的是类级别的自定义验证程序。需要类级，因为如果要获取实体，则需要访问整个对象而不仅仅是单个值。

验证程序本身可能如下所示：

namespace Vendor\YourBundle\Validation\Constraints;

use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

class StatusValidator extends ConstraintValidator
{
    protected $container;

    public function __construct(ContainerInterface $container)
    {
        $this->container = $container;
    }

    public function validate($status, Constraint $constraint)
    {

        $em = $this->container->get('doctrine')->getEntityManager('default');

        $previousStatus = $em->getRepository('YourBundle:Status')->findOneBy(array('id' => $status->getId()));

        // ... do something with the previous status here

        if ( $previousStatus->getValue() != $status->getValue() ) {
            $this->context->addViolationAt('whatever', $constraint->message, array(), null);
        }
    }

    public function getTargets()
    {
        return self::CLASS_CONSTRAINT;
    }

    public function validatedBy()
    {
       return 'previous_value';
    }
}

...然后将验证器注册为服务并将其标记为验证器

services:
    validator.previous_value:
        class: Vendor\YourBundle\Validation\Constraints\StatusValidator

        # example! better inject only the services you need ... 
        # i.e. ... @doctrine.orm.entity_manager

        arguments: [ @service_container ]         
        tags:
            - { name: validator.constraint_validator, alias: previous_value }

最后使用状态实体的约束（即使用注释）

use Vendor\YourBundle\Validation\Constraints as MyValidation;

/**
 * @MyValidation\StatusValidator
 */
class Status 
{