Symfony5handleRequest更新原始collectionType物件

遵循此處的官方 Symfony 檔案時，我無法使我的邏輯正常作業：https : //symfony.com/doc/current/form/form_collections.html#allowing-tags-to-be-removed

根據示例，我需要獲取原始標簽，然后在處理表單后將它們與新標簽進行比較。

在我的例子中，我有一個Purchase物體，它可以有一個PurchaseProducts(ManyToMany)的集合。就我而言，當我更改 a 時，PurchaseProduct我需要更新已洗掉的購買的庫存。但是，無論我如何獲得原始 PurchaseProducts，在 $form->handleRequest() 之后，它們都會更新為新值，并且我會丟失有關原始值的任何資訊。

片段用邏輯形成我的控制器：

 /** @var Purchase $purchase */
    $purchase = $this->getDoctrine()
        ->getRepository(Purchase::class)
        ->find($id);

    if (!$purchase) {
        $this->addFlash('error', 'Purchase not found');
        return $this->redirect($this->generateUrl('purchase_list'));
    }

    $originalProducts = new ArrayCollection();
    foreach ($purchase->getPurchaseProducts() as $purchaseProduct) {
        $originalProducts->add($purchaseProduct);
    }

    $form = $this->createForm(PurchaseType::class, $purchase);

    if ($request->isMethod('POST')) {

        dump($originalProducts); // Original entities are here

        $form->handleRequest($request);

        dump($originalProducts);die; // Original entities are updated with the new ones

        ...

        // This will not work since originalProducts already has the new entities
        foreach ($originalProducts as $purchaseProduct) {
            if (false === $purchase->getPurchaseProducts()->contains($purchaseProduct)) {
                // update stock here
            }
        }

我嘗試了很多選項，比如克隆、查詢資料庫等等，但是在 handleRequest 之后我總是得到相同的更新物體。為什么？

uj5u.com熱心網友回復：

行為說明

正如您所指的表單處理器的"allow_delete" => true或"allow_add" => true概念。提交表單時，副本中出現的集合中的物體屬性更改是預期行為。但是，該$originalProducts集合將不包含任何新物體 ( new PurchaseProduct())。

發生這種情況是因為 PHP 通過參考傳遞物件，即將PurchaseProduct物件傳遞給ArrayCollection. 這意味著對嵌入的表單物件所做的任何更改都應用于集合Purchase:::$purchaseProducts和$originalProducts集合，因為它們是相同的PurchaseProduct物件（按參考）。

但是，當它們在Purchase:::$purchaseProducts之后從集合中移除時$form->handleRequest($request)，物件仍將存在于$originalProducts集合中。如果您的物體不包含必要的邏輯，您可以比較這兩個集合以將它們從物體管理器或物體集合中洗掉。

使用 ArrayObject 和 Foo 物件的示例：https ://3v4l.org/oLZqO#v7.4.25

Class Foo
{
    private $id;
    
    public function __construct()
    {
        $this->id = uniqid('', false);
    }
    
    public function setId($id)
    {
        $this->id = $id;
    }
}

//initial state of Purchase::$purchaseProducts
$foo1 = new Foo();
$foo2 = new Foo();
$a = new ArrayObject([$foo1, $foo2]); 

//Create Copy as $originalProducts
$b = new ArrayObject();
foreach ($a as $i => $foo) {
    $b->offsetSet($i, $foo);
}

//form submission
$foo1->setId('Hello World');
$a->offsetUnset(1);

結果

Initial state of Copy:
ArrayObject::__set_state(array(
   0 => 
  Foo::__set_state(array(
     'id' => '6182c24b00a21',
  )),
   1 => 
  Foo::__set_state(array(
     'id' => '6182c24b00a28',
  )),
))
-----------------------
Form Submitted ID Changed in Copy:
ArrayObject::__set_state(array(
   0 => 
  Foo::__set_state(array(
     'id' => 'Hello World',
  )),
   1 => 
  Foo::__set_state(array(
     'id' => '6182c24b00a28',
  )),
))
-----------------------
Source has foo2 entity removed:
ArrayObject::__set_state(array(
   0 => 
  Foo::__set_state(array(
     'id' => 'Hello World',
  )),
))
-----------------------
Copy still contains both entities:
ArrayObject::__set_state(array(
   0 => 
  Foo::__set_state(array(
     'id' => 'Hello World',
  )),
   1 => 
  Foo::__set_state(array(
     'id' => '6182c24b00a28',
  )),
))

決議

根據您想要的結果，有多種方法可用于檢測和處理更改，例如Change Tracking Policies.

確定物體發生了什么變化的另一種方法是$em->getUnitOfWork()->getEntityChangeSet($entity)檢索提議給條令的物體的變化。

代碼建議

To ensure the request is not misinterpreted, you should always handle the form request (regardless of the request method) and verify that the form was submitted/valid. This is because the handleRequest method triggers multiple events depending on the request method.

/** @var Purchase $purchase */
    $purchase = $this->getDoctrine()
        ->getRepository(Purchase::class)
        ->find($id);

    if (!$purchase) {
        $this->addFlash('error', 'Purchase not found');
        return $this->redirect($this->generateUrl('purchase_list'));
    }

    $originalProducts = new ArrayCollection();
    foreach ($purchase->getPurchaseProducts() as $purchaseProduct) {
        $originalProducts->add($purchaseProduct);
    }

    $form = $this->createForm(PurchaseType::class, $purchase);
    dump($originalProducts); // Original entities are here
    $form->handleRequest($request);

    if ($form->isSubmitted() && $form->isValid()) {
        dd($originalProducts); // dump die as dd() - Original entities are updated with the new ones

        //...

        // This will not work since originalProducts already has the new entities
        foreach ($originalProducts as $purchaseProduct) {
            if (false === $purchase->getPurchaseProducts()->contains($purchaseProduct)) {
               //remove original from the Purchase entity
            }
        }

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