深入克隆一个对象：克隆vs序列化 [英] Deep cloning an object : Clone vs Serialize

问题描述

我有这个函数duplicateCourseAction，其目的是...复制一个Course对象

I have this function duplicateCourseAction whose goal is to ... duplicate a Course object

public function duplicateCourseAction(Request $request) {
    if ($this->getRequest()->isXmlHttpRequest() == false) {
        return new Response("Bad request", 405);
    }

    $em = $this->getDoctrine()->getManager();
    $parameters = $request->request->all();
    $course = $em->getRepository('EntTimeBundle:Course')->findOneById($parameters['id']);
    $duplicate = clone $course;
    $duplicate->setDate(new \DateTime($parameters['date']));
    $em->persist($duplicate);
    $em->flush();
    return new Response("200");
}

根据文档，克隆关键字做一个表面复制（即一个参考文献）。
这显然不是我想要的，因为我的课程实体包含与其他实体的许多关系，我宁愿想要一个值拷贝。

According to documentations, "clone" keyword make a surface copy (ie. a reference copy). This is clearly not what I want because my Course entity contains many relations to others entities, I would rather want a values copy.

我发现了unserialize serialize（object））trick：

I discovered the unserialize(serialize(object)) trick :

public function duplicateCourseAction(Request $request) {
    if ($this->getRequest()->isXmlHttpRequest() == false) {
        return new Response("Bad request", 405);
    }

    $em = $this->getDoctrine()->getManager();
    $parameters = $request->request->all();
    $course = $em->getRepository('EntTimeBundle:Course')->findOneById($parameters['id']);
    $duplicate = unserialize(serialize($course));
    $duplicate->setDate(new \DateTime($parameters['date']));
    $em->persist($duplicate);
    $em->flush();
    return new Response("200");
}

但是我在Doctrine中有这个错误：

But I have this error with Doctrine :

注意：未定义的索引：000000003ed2e9ea00000000ee270fde在/home/mart_q/Diderot/ent/vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php行2776

推荐答案

您可以通过覆盖 __ clone（）方法来控制什么是克隆的您的课程实体。您可以将 id 设置为 null ，如果需要深入复制，则可以克隆引用的对象。

You can control what exactly gets cloned by overriding the __clone() method in your Course entity. You can set id to null and clone referenced objects if you need a deep copy.

序列化/非序列化感觉像一个黑客，所以我建议不要使用它。

The serialization/unserialization feels like a hack, so I recommend against using it.

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