Mastering Doctrine Relations in Symfony 4!

Hey Mohamed K.

At the moment we do not have that course in our plans, but we *do* hear all our customer's suggestions, so, thanks for letting us know what would you like to learn!
You can check our upcoming tutorials here: https://knpuniversity.com/c...

Have a nice day :)

To add more info, we will definitely do something with API's, and relatively soon. I'd like to do a tutorial about APIPlatform, which is AWESOME. But, we may also do something that sticks a bit more to normal Symfony features.

About Angular specifically, we do have a React tutorial planned, and may do some Vue stuff in the future. But, Angular is not currently on my radar. However, fortunately, there's nothing really special about using Symfony & any of the front-end frameworks. For authentication, the easiest thing to do is use normal "form login" authentication, then allow your AJAX requests to use the session cookie. Then, it's all just normal API/AJAX requests.

If you have any other questions, let us know!

Cheers!

Angular and RxJs Observables are so sweet! Redux and ngRx will be nice too.

Hey @Ariel!

Excellent question! Yes, definitely :). We will update this soon for Symfony 5, but Doctrine relations have not changed in... really any way that I can think of between Symfony 4 and 5. This tutorial will serve you well. And of course, if you have any doubts, you can ask us any questions.

Cheers!

Hi Ryan,

Thank you for your quick response :)

Ariel

Hey PHP Fan,

Thank you for your interest in SymfonyCasts tutorials! We're sorry for the delay with releasing this tutorial for Symfony 5 track. We're working on it, most probably it might be our next tutorial, or next after another tutorial I think. But unfortunately, no more accurate estimations yet. You can watch for our upcoming tutorials on this page: https://symfonycasts.com/co... - if anything is changed - it will be displayed there.

Cheers!

Hey be_tnt!

It sounds like you are definitely understanding the "problem" correctly :).

The problem is when I save the cart to database, even if the product already exists, it does not recognize it.

Yea... this looks "weird" to me also. If you already have a Product saved into the database, and then you create a new CartProduct and set that Product onto it, you should not need to explicitly call persist on that Product (or cascade={"persist"}, which is just the same thing as manually persisting). So, I agree, you should not need to have that second persist - I think something weird is going on.

Here's what I would do to debug:

Add the cascade=persist to the product field on CartProduct... just to see what happens. Does it all save normally? Or does this (crazily) create a NEW Product in the database? This will give us a hint about what's going on. According to the error, it sort of seems like Doctrine thinks (for some reason) that this is a NEW Product it should insert.

Based on what this, we can keep debugging :).

Cheers!

Hey weaverryan ,

I have done what you suggested and I got another error (quite strange btw):

Notice: Undefined index: 000000002e4d2d6e0000000027619249

Not really helpful, isn't it ? ;)

A little bit more details:

Uncaught PHP Exception ErrorException: "Notice: Undefined index: 000000002e4d2d6e0000000027619249" at /vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php line 2997

this is about these lines:

public function getEntityIdentifier($entity)
{
return $this->entityIdentifiers[spl_object_hash($entity)];
}

Hope this help!

Hey be_tnt !

Sorry for my slow reply! And woh! Something is very strange here! This simply... shouldn't happen. So, if you're still with me, we need to dig further! A few things:

1) Are you doing anything strange like $entityManager->clear() in your app... or are you doing this work in a test? Or, $entityManager->detach(). Everything makes it feel like you queried for CartProduct object... but then Doctrine... sorta "forgets" that it knows about it. Specifically, the UnitOfWork keeps track of every entity that it has queried for or saved during a request. The error we're seeing (I believe) is that you've queried for this CartProduct... then when everything saves... it's as if it's forgotten that it queried for this object.

2) Can you post a screenshot of the full stack trace? And maybe, if you can, the code you have for doing all the saving and the annotations for the relationships :).

It definitely smells to me like some very subtle thing is causing lots of weirdness. Things aren't behaving correctly!

Cheers!

Huh my comments were removed because they were detected as spams. Maybe because of the stack trace. Let me post the message without :)

The Cart class:

/**
* @ORM\OneToMany(
* targetEntity="App\Entity\CartProduct",
* mappedBy="cart",
* )
*/
private $products;

The cart object is created and saved to database based on products saved in session. Below the way I used to save products in session:

$items[$product->getId()] = [
'product' => $product,
'qty' => $request->request->get('add_item_to_cart')['quantity']
];
$this->session->set('shoppingCart/items', $items);

The CartProduct class:

/**
* @ORM\ManyToOne(targetEntity="App\Entity\Cart", inversedBy="products")
* @ORM\JoinColumn(nullable=false)
*/
private $cart;

/**
* @ORM\ManyToOne(targetEntity="App\Entity\Product")
* @ORM\JoinColumn(
* nullable=false
* )
*
*/
private $product;

In the cart controller:

$items = $this->session->get( 'shoppingCart/items' );
foreach ( $items as $item ) {
$product = new CartProduct();
$product->setProduct( $item['product'] );
$product->setQuantity( $item['qty'] );
$em->persist( $product );
$cart->addProducts( $product );
}

$em->persist( $cart );
$em->flush();

The $item['product'] is a Product object.

Hope this helps :)

be_tnt ,

No idea of what could be the issue here?
Thx !

Hi weaverryan !

Thx for helping! To answer to your questions:

1) No, nothing special in my code.
2) Let me try to explain what I am trying to do. The user add products to a cart. This is kept in session:

// add the new item in cart
$items[$product->getId()] = [
'product' => $product,
'qty' => $request->request->get('add_item_to_cart')['quantity']
];
$this->session->set('shoppingCart/items', $items);

When the user starts the payment process, this cart is saved to database:

$cart = new Cart();
$cart->setUser( $user );
$items = $this->session->get( 'shoppingCart/items' );
foreach ( $items as $item ) {
$product = new CartProduct();
$product->setProduct( $item['product'] );
$product->setQuantity( $item['qty'] );
$em->persist( $product );
$cart->addProducts( $product );
}

$em->persist( $cart );
$em->flush();

The Cart class:

/**
* @ORM\OneToMany(
* targetEntity="App\Entity\CartProduct",
* mappedBy="cart",
* )
*/
private $products;

The CartProduct class:

/**
* @ORM\ManyToOne(targetEntity="App\Entity\Cart", inversedBy="products")
* @ORM\JoinColumn(nullable=false)
*/
private $cart;

/**
* @ORM\ManyToOne(targetEntity="App\Entity\Product")
* @ORM\JoinColumn(
* nullable=false
* )
*
*/
private $product;

The full stack trace (the original one):

Doctrine\ORM\ORMInvalidArgumentException:
Multiple non-persisted new entities were found through the given association graph:

* A new entity was found through the relationship 'App\Entity\CartProduct#product' that was not configured to cascade persist operations for entity: App\Entity\Product@000000001057f61a000000007afc015d. To solve this issue: Either explicitly call EntityManager#persist() on this unknown entity or configure cascade persist this association in the mapping for example @ManyToOne(..,cascade={"persist"}). If you cannot find out which entity causes the problem implement 'App\Entity\Product#__toString()' to get a clue.
* A new entity was found through the relationship 'App\Entity\CartProduct#product' that was not configured to cascade persist operations for entity: App\Entity\Product@000000001057f7e8000000007afc015d. To solve this issue: Either explicitly call EntityManager#persist() on this unknown entity or configure cascade persist this association in the mapping for example @ManyToOne(..,cascade={"persist"}). If you cannot find out which entity causes the problem implement 'App\Entity\Product#__toString()' to get a clue.

at vendor/doctrine/orm/lib/Doctrine/ORM/ORMInvalidArgumentException.php:105
at Doctrine\ORM\ORMInvalidArgumentException::newEntitiesFoundThroughRelationships(array(array(array('fieldName' => 'product', 'joinColumns' => array(array('name' => 'product_id', 'unique' => false, 'nullable' => false, 'onDelete' => null, 'columnDefinition' => null, 'referencedColumnName' => 'id')), 'cascade' => array(), 'inversedBy' => null, 'targetEntity' => 'App\\Entity\\Product', 'fetch' => 2, 'type' => 2, 'mappedBy' => null, 'isOwningSide' => true, 'sourceEntity' => 'App\\Entity\\CartProduct', 'isCascadeRemove' => false, 'isCascadePersist' => false, 'isCascadeRefresh' => false, 'isCascadeMerge' => false, 'isCascadeDetach' => false, 'sourceToTargetKeyColumns' => array('product_id' => 'id'), 'joinColumnFieldNames' => array('product_id' => 'product_id'), 'targetToSourceKeyColumns' => array('id' => 'product_id'), 'orphanRemoval' => false), object(Product)), array(array('fieldName' => 'product', 'joinColumns' => array(array('name' => 'product_id', 'unique' => false, 'nullable' => false, 'onDelete' => null, 'columnDefinition' => null, 'referencedColumnName' => 'id')), 'cascade' => array(), 'inversedBy' => null, 'targetEntity' => 'App\\Entity\\Product', 'fetch' => 2, 'type' => 2, 'mappedBy' => null, 'isOwningSide' => true, 'sourceEntity' => 'App\\Entity\\CartProduct', 'isCascadeRemove' => false, 'isCascadePersist' => false, 'isCascadeRefresh' => false, 'isCascadeMerge' => false, 'isCascadeDetach' => false, 'sourceToTargetKeyColumns' => array('product_id' => 'id'), 'joinColumnFieldNames' => array('product_id' => 'product_id'), 'targetToSourceKeyColumns' => array('id' => 'product_id'), 'orphanRemoval' => false), object(Product))))
(vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php:3445)
at Doctrine\ORM\UnitOfWork->assertThatThereAreNoUnintentionallyNonPersistedAssociations()
(vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php:364)
at Doctrine\ORM\UnitOfWork->commit(null)
(vendor/doctrine/orm/lib/Doctrine/ORM/EntityManager.php:359)
at Doctrine\ORM\EntityManager->flush()
(src/Controller/CartController.php:92)
at App\Controller\CartController->cart(object(CartRepository), object(UserAddressRepository), object(Request), object(EntityManager))
(vendor/symfony/http-kernel/HttpKernel.php:151)
at Symfony\Component\HttpKernel\HttpKernel->handleRaw(object(Request), 1)
(vendor/symfony/http-kernel/HttpKernel.php:68)
at Symfony\Component\HttpKernel\HttpKernel->handle(object(Request), 1, true)
(vendor/symfony/http-kernel/Kernel.php:198)
at Symfony\Component\HttpKernel\Kernel->handle(object(Request))
(public/index.php:25)

Hope this help!

I have finally changed my way of doing things. Before adding a product in the cart, I get it again from the db (to get the latest information in case for ex the price has changed) and then add it to the cart:

So my code becomes:

$items = $this->session->get( 'shoppingCart/items' );
foreach ( $items as $item ) {
$cartProduct = new CartProduct();
// get the latest information about the product saved in database
$product = $product_repository->findOneBy([
'id' => $item['product'],
'isDeleted' => 0,
'isEnabled' => 1
]);
if (!empty($product)) {
$cartProduct->setProduct( $product );
$cartProduct->setQuantity( $item['qty'] );
$cart->addProducts( $cartProduct );
}
}

$em->persist( $cart );
$em->flush();

Thx!

Hey be_tnt !

Bahhh, sorry about my slow reply! I was just finally working through some things - it's SymfonyCon week, so we're a little extra busy. Anyways, I'm super happy you got it sorted! (And sorry about the SPAM issue - that's lame).

Let me give you a bit of context on "why" this was all happening... in case it's useful :). When you store the Cart object in the session (which is a totally legal thing to do!) something funny happens the next time you "fetch" it out of the cart. Here is the flow:

A) Request 1: you create a Cart object and insert it into the database. It gets id 1!
B) Request 1: you then put that Cart in the session
// 2 minutes go by, user adds another Product to their Cart
C) Request 2: you fetch the Cart out of the session. It is (of course) id 1.

This is enough to describe the issue. When you are on that "second" request (step C), Doctrine has not queried for the Cart object on that request. Doctrine keeps track of all the objects it has saved or queried for during a request (so that if you query for the same object twice, it skips making a 2nd query and just gives you back the same object). But this is NOT the same request as steps (A) and (B). And so, when you persist/flush the Cart object, Doctrine "thinks" it's a new object and inserts it. The key to understand why is this: when Doctrine tries to determine whether an object should be updated in the database versus inserted, it does not simply check to see if the object (e.g. Cart) has an "id" or not. Nope, it checks its "identity map" - which is a fancy way of saying - it asks itself: "Have I queried for or saved this object on this request?". If it has, then it knows about it and updates it. If it has not, then it tries to insert it (also, in this situation, it requires you to call persist() - which is the reason for the original error).

Phew! So actually, one solution is to store the Cart id in the session, not the entire object. We do something similar here on SfCasts - we only store the cart "id". We have a CartManager service, however, that helps us get the object. Basically, we all $cartManager->getCart() and IT takes care to read the cart "id" from the session, query for it, and return it. So we avoid the problem and still get a really nice user experience where we don't need to worry about querying for the Cart in the controller.

I hope this helps - even if it wasn't as timely as I would have liked!

Cheers!

Many thanks for this great explanation !!! That was important for me to understand the reason to continue to improve my knowledge on symfony.

Hey bartek

Nope, it doesn't mean it's a bad practice. I usually use "cascade on persist" when I work with collections, so then I don't need to persist new items added to a collection.
You can find more info about cascade operations here: https://www.doctrine-projec...

Cheers!

Hey Alexander,

Very rough approximation - it will be started releasing after "Doctrine & the Database" course, probably on the next week. We also want to start releasing ReactJS course very soon, so these two courses on the way to be released.

Cheers!

Ok, great! Thanx for the quick reply!

Hey Alexander Enlund

I can't give you a release date yet, but we already have a tutorial about forms, it's made on Symfony3, but nothing serious has changed https://knpuniversity.com/s...

And, if you want to learn more about how to customize your form's rendering, then you may also like to watch this tutorial: https://knpuniversity.com/s...

Cheers!

okay... Thanks for the fast reply and the recommendations!