为什么Doctrine \\ ORM \\ Configuration的“ DoctrineProxies”对象包含宇宙？

Question

In my ORM code I have an Entity with a field fined like so: 在我的ORM代码中，我有一个实体，其字段的罚款如下：

//part of entity class Item:
/** @Column(name="product_id", type="integer") */
private $productId;

I then executed this code: 然后执行以下代码：

//3 lines ~straight out of Doctrine configuration to get EntityManager
include 'config/doctrine-config.php';
$config = Setup::createAnnotationMetadataConfiguration($paths, $isDevMode);
$em = EntityManager::create($dbParams, $config);

//my own code to retrieve an entity instance:
$instance = $em->find(Item::class, 2);
print_r($instance);

And this is the output I get (skipping few other similar properties): 这是我得到的输出（跳过一些其他类似的属性）：

Application\Entity\Item Object
(
    [id:Application\Entity\Item:private] => 2
    [description:Application\Entity\Item:private] => Product Kit
    [productId:Application\Entity\Item:private] => -1
)

Note how there are 6 (six) lines above that came out of print_r() function. 请注意， print_r()函数的上方有六（六）行。

And everything was fine, Until 一切都很好，直到

Next, I have changed the $productId column to ManyToOne Relationship on my Item Entity class, like so: 接下来，我将Item Entity类的$productId列更改为ManyToOne Relationship，如下所示：

/** 
 * @ManyToOne(targetEntity="Product", inversedBy="id")
 * @JoinColumn(name="product_id", referencedColumnName="id")
 */
private $productId;

I ran the same code. 我运行了相同的代码。

OUT CAME THE UNIVERSE OF 2,392,600 LINES, WHAT? 达到2,392,600行的宇宙，这是什么？

Two million, three hundred and ninety two thousand, six hundred lines lines of print_r output. 两百三十二万二千六百行 print_r输出行。

looking at the print-out I see that DoctrineProxies\\__CG__\\Application\\Entity\\Product Object contains 2,392,564 lines printed by print_r 查看打印输出，我看到DoctrineProxies\\__CG__\\Application\\Entity\\Product对象包含由print_r打印的2,392,564行

Question: 题：

What is exactly in this object and why is it so big as to take up nearly 300Mb of disk space when printed out? 这个对象到底是什么？为什么它这么大，以至于在打印输出时要占用近300Mb的磁盘空间？

I cannot help but wonder if such complexity is apt to cause performance issues in every-day code. 我忍不住想知道，这种复杂性是否易于在日常代码中引起性能问题。 For example, I am not printing out the contents of the $instance variable in my every-day code, but I surely return the humongousness from a method call. 例如，我没有在日常代码中打印$instance变量的内容，但是我肯定从方法调用中返回了笨拙。 Does that mean it is a 300Mb variable that gets passed from ie the $em->find(Item::class, 2); 这是否意味着它是从$em->find(Item::class, 2);传递的300Mb变量$em->find(Item::class, 2); call above? 在上面打电话吗？

(Very) Partial Listing （非常）部分上市

Answer 1

You can't dump a proxy object without XDebug or similar tools (which limit the dumped object size). 没有XDebug或类似工具（限制了转储对象的大小），您将无法转储代理对象。

The problem is really, really simple: 问题非常非常简单：

Proxy -> references EntityManager -> references UnitOfWork -> contains Proxy 代理->引用EntityManager->引用UnitOfWork->包含代理

This obviously leads to a recursive data-structure dump, which in turn leads to a mess any time you try to dump it without sensible limits. 显然，这会导致递归的数据结构转储，进而在您每次尝试无合理限制地转储时都会导致混乱。

Answer 2

DoctrineProxies\\__CG__\\Application\\Entity\\Product是一个代理类...这意味着该理论实际上不会从数据库中获取实体（以提高性能），除非需要它（即调用$product->getName()这些代理类彼此之间处于递归循环中，并且您看到的类非常大...除非真正深入地了解，否则实际上不需要的大多数信息...您永远不要在新的symfony 2.7中使用print_r ... +我认为在调试模式下有一个称为dump()的函数...如果您使用该函数来打印具有循环保护的实体，并且它仅显示参考数字...您也可以使用\\Doctrine\\Common\\Util\\Debug::dump()也将打印出比2 ^ 234234234行小的列表...

为什么Doctrine \\ ORM \\ Configuration的“ DoctrineProxies”对象包含宇宙？

问题描述

2 个解决方案

解决方案1
3 已采纳 2016-05-06 16:18:37

解决方案2
1 2016-05-06 16:10:35

为什么Doctrine \\ ORM \\ Configuration的“ DoctrineProxies”对象包含宇宙？

问题描述

2 个解决方案

解决方案1 3 已采纳 2016-05-06 16:18:37

解决方案2 1 2016-05-06 16:10:35

解决方案1
3 已采纳 2016-05-06 16:18:37

解决方案2
1 2016-05-06 16:10:35