title: Why is my Symfony2 @UniqueEntity constraint not working at all?
body: <p>I have the following entity class in my application:</p>
  
  <pre><code>&lt;?php
  
  namespace ...;
  
  // use ...
  use Doctrine\ORM\Mapping as ORM;
  use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;;
  // ...
  
  /**
   * @ORM\Table(name="sc_user")
   * @ORM\Entity(repositoryClass="...\UserRepository")
   * @ORM\HasLifecycleCallbacks()
   * @UniqueEntity(fields={"email", "username"})
   */
  class User implements UserInterface, \Serializable, EquatableInterface
  {
      /**
       * @var integer $id
       *
       * @ORM\Column(name="id", type="integer")
       * @ORM\Id
       * @ORM\GeneratedValue(strategy="AUTO")
       */
      private $id;
  
      /**
       * @var string $email
       *
       * @ORM\Column(name="email", type="string", length=255, unique=true)
       *
       * @Assert\NotBlank(groups={"registration"})
       * @Assert\Email(groups={"registration"})
       */
      private $email;
  
      /**
       * @var string $username
       *
       * @ORM\Column(name="username", type="string", length=32, unique=true)
       *
       * @Assert\NotBlank(groups={"registration"})
       */
      private $username;
  
      // ...
  }
  </code></pre>
  
  <p>The @UniqueEntity constraint is being ignored. I tried different flavors including:</p>
  
  <pre><code>@UniqueEntity(fields={"email", "username"})
  </code></pre>
  
  <p>and </p>
  
  <pre><code>@UniqueEntity(fields={"email"})
  @UniqueEntity(fields={"username"})
  </code></pre>
  
  <p>and, as per the Symfony2 documentation here: <a href="http://symfony.com/doc/current/reference/constraints/UniqueEntity.html">http://symfony.com/doc/current/reference/constraints/UniqueEntity.html</a></p>
  
  <pre><code>@UniqueEntity("email")
  @UniqueEntity("username")
  </code></pre>
  
  <p>Nothing I do, works. Instead of getting a form validation error as expected, I am getting the following exception:</p>
  
  <blockquote>
    <p>SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry
    'admin@scire.com' for key 'UNIQ_D8183973E7927C74'</p>
  </blockquote>
  
  <p>This is just wrong! Does anyone know how to fix this issue?</p>