[LiveComponent] Implement hydratation of DTO object

[WebMamba]

Q	A
Bug fix?	yes
New feature?	no
Tickets	Fix #955
License	MIT

With this PR you van easily use DTO with your LiveComponents.

class CustomerDetails
{
    public string $name;
    public Address $address;
    public string $city;
}

class Address
{
    public string $street;
    public string $postCode;
}

#[AsLiveComponent(name: 'CustomerDetails')]
class CustomerDetailsComponent
{
    use DefaultActionTrait;

    #[ExposeInTemplate]
    public string $hello = 'hello';

    #[LiveProp(writable: true)]
    public ?CustomerDetails $customerDetails = null;

    public function mount(): void
    {
        $this->customerDetails = new CustomerDetails();
        $this->customerDetails->name = 'Matheo';
        $this->customerDetails->city = 'Paris';
        $this->customerDetails->address = new Address();
        $this->customerDetails->address->street = '3 rue de la Paix';
        $this->customerDetails->address->postCode = '92270';
    }

    #[LiveAction]
    public function switch(): void
    {
        $this->customerDetails = new CustomerDetails();
        $this->customerDetails->name = 'Paul';
        $this->customerDetails->city = 'Paris';
        $this->customerDetails->address = new Address();
        $this->customerDetails->address->street = '3 rue des mimosas';
        $this->customerDetails->address->postCode = '92270';
    }
}

<div {{ attributes }}>
    <p>{{ customerDetails.name }}</p>
    <p>{{ customerDetails.address.street }}</p>
    <button
            data-action="live#action"
            data-action-name="switch"
    >Switch</button>
</div>

[weaverryan]

Fantastic!!!

[weaverryan]

We should centralize this - as it's repeated in https://github.com/symfony/ux/blob/2.x/src/LiveComponent/src/Metadata/LiveComponentMetadataFactory.php

[weaverryan]

Any reason for this change and the changes above? We already have a $propMetadata variable - is it not correct for some reason?

[WebMamba]

The goal here is for each item of the array to go through the dehydrate method. I did that to support array of DTOs

[weaverryan]

That makes sense - but I think the old code already did that. The main difference between the old and new code just seems to be that the old called ->dehydrateObjectValue() on each item and the new code calls ->dehydrateValue().

But there is an important detail in the original code: to determine the "type" of each item in the array, we should NOT use $objectItem::class. Instead, we need to read the "property info" off of the property. Otherwise, we may allow for a value to be dehydrated that won't be able to be rehydrated later. Example:

class Foo
{
    public array $dtos1 = [];

    /** @var Dto[] */
    public array $dtos2 = [];
}

$foo = new Foo();
$foo->dtos1 = [new Dto()];
$foo->dtos2 = [new Dto()];

In this situation, the dtos1 property is invalid: we will not be able to hydrate this. We know that dtos1 holds an array, but an array of what? That is the purpose of the $propMetadata->collectionValueType()->getClassName();: it tells us what the "metadata" (e.g. phpdoc) tells us the "type" of each item in the collection is. If that's missing, we COULD still successfully dehydrate, but hydration would fail. So, instead, we fail during dehydration to warn the user early.

[weaverryan]

WOW. We're down to the last details. Looking at your test cases got me really excited though... :D. Can you also add some documentation? Thank you!

[weaverryan]

I think we should use https://symfony.com/doc/current/components/property_info.html#list-information instead of ReflectionClass::getProperties(). It'll let us also support private properties with getters & setters (I believe the property info will only return public properties + private properties with a getter).

[weaverryan]

I think this isn't resolved yet. We're using processAccessor to read the values, but not property info to list the properties.

[WebMamba]

Thanks, Ryan for your review! I just gonna need some help for the docs and the errors messages 😁

[weaverryan]

I think this isn't resolved yet. We're using processAccessor to read the values, but not property info to list the properties.

[weaverryan]

THANK YOU Matheo! This works AWESOME - it's a dream. I put some comments about the docs, but they are so minor, I will make them in a different PR.