symfony4.1.3无法解析导入的Doctrine \ Bundle \ FixturesBundle \ Fixture

Question

我正在学习Symfony 4.1.3。

我已经用作曲家创建了演示项目：

composer -V: Composer version 1.7.1 2018-08-07 09:39:23

我已经安装了orm-fixtures：

composer require orm-fixture
    Using version ^3.0 for doctrine/doctrine-fixtures-bundle
    ./composer.json has been updated
    Loading composer repositories with package information
    Updating dependencies (including require-dev)
    Restricting packages listed in "symfony/symfony" to "4.1.*"
    Nothing to install or update
    Generating autoload files
    ocramius/package-versions:  Generating version class...
    ocramius/package-versions: ...done generating version class

然后我创建了夹具：

php bin/console make:fixtures

已创建文件src / DataFixtures / ArticleFixtures.php：

<?php
namespace App\DataFixtures;

use Doctrine\Common\Persistence\ObjectManager;
use Doctrine\Bundle\FixturesBundle\Fixture;

class ArticleFixtures extends Fixture
{

    public function load(ObjectManager $manager)
    {
        // $product = new Product();
        // $manager->persist($product);
        $manager->flush();
    }
}

然后use Doctrine\Bundle\FixturesBundle\Fixture;行用红色下划线显示以下消息：

The import Doctrine\Bundle\FixturesBundle\Fixture cannot be resolved

我被这个错误困扰，我不知道该如何解决。 任何帮助将不胜感激。