条令不起作用

我有一张发票。在本表中,我有:

invoice_id 列,它是 PRIMARY KEY auto_increment .

二- invoice_number

在我的实体里我有这个代码

use Doctrine\ORM\Mapping as ORM;
use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;

/**
 * Invoices
 *
 * @ORM\Table(name="invoices", uniqueConstraints={@ORM\UniqueConstraint(name="invoice_number", columns={"invoice_number"})})
 * @ORM\Entity
 * @ORM\HasLifecycleCallbacks
 *
 *  @UniqueEntity(fields="invoiceNumber", message="invoice number is already exist")
 */
class Invoices
{

    /**
     * @var integer
     *
     * @ORM\Column(name="invoice_id", type="integer", nullable=false)
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="IDENTITY")
     */
    private $invoiceId;

    /**
     * @var string
     *
     * @ORM\Column(name="invoice_number", type="string", length=50, nullable=true, unique=true)
     */
    private $invoiceNumber;

在我使用的控制器中 $form->isValid() 这样地

$form->handleRequest($request);
if ($form->isSubmitted() && $form->isValid()) {

}

我用这个代码呈现字段

{{ form_label(form.salesInvoice.invoice.invoiceNumber, null, {'label_attr':{'class':'black'}}) }} <span class="required">*</span>
{{ form_widget(form.salesInvoice.invoice.invoiceNumber) }}
<div class="required"> {{ form_errors(form.salesInvoice.invoice.invoiceNumber) }}</div>

当我试图保存发票号码重复的发票时,我遇到了这个错误

SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '1230008' for key 'invoice_number'

发票号已存在