After #51342 whenLoaded doesn't return null when needed

[jeanroloff]

Laravel Version

11.20.0

PHP Version

8.3.16

Database Driver & Version

No response

Description

Before version 11.20.0 the following code would return null

class CommentResource extends JsonResource
{
    public function toArray($request)
    {
        return [
            'value' => $this->whenLoaded('entity', $this->resource->entity->comment),
        ];
    }
}

If $this->resource->entity->comment is actually null on the database, the code correctly returns the following output in the api.

{
"value": null
}

But after the related issue got merged #51342, the code doenst return null anymore; it returns the entity that is being loaded, which caused unexpected results in our source code today.

{
"value": {
// entity object
}
}

I really think that we should be able to return null if the value is actually null when using the whenLoaded function

Steps To Reproduce

Check description.

[crynobone]

Hey there, thanks for reporting this issue.

We'll need more info and/or code to debug this further. Can you please create a repository with the command below, commit the code that reproduces the issue as one separate commit on the main/master branch and share the repository here?

Please make sure that you have the latest version of the Laravel installer in order to run this command. Please also make sure you have both Git & the GitHub CLI tool properly set up.

laravel new bug-report --github="--public"

Do not amend and create a separate commit with your custom changes. After you've posted the repository, we'll try to reproduce the issue.

Thanks!

[rodrigopedra]

@crynobone this is a reproduction case:

<?php // ./routes/web.php

use App\Models\User;
use Illuminate\Http\Resources\Json\JsonResource;
use Illuminate\Support\Facades\Route;
use Illuminate\Support\Fluent;

Route::get('/test', function () {
    $user = new User();

    $user->setRelation('contact', new Fluent(['phone' => '555', 'email' => null]));

    return new class($user) extends JsonResource
    {
        public function toArray($request)
        {
            return [
                'contact' => $this->whenLoaded('contact', $this->resource->contact->email),
            ];
        }
    };
});

Before PR #51342

{
    "contact": null
}

After PR #51342

{
    "contact": {
        "phone": "555",
        "email": null
    }
}

Please see next comment for workaround

[rodrigopedra]

@jeanroloff

You can work around this by passing a closure as the value parameter:

class CommentResource extends JsonResource
{
    public function toArray($request)
    {
        return [
            'value' => $this->whenLoaded('entity', fn ($entity) => $entity->comment),
        ];
    }
}

As such, $value won't be null, and thus the changes introduced by PR #51342 won't affect the results.

It is actually better to use the closure to avoid lazy loading the entity relation, even when it wasn't previously loaded.

In practice, your code always eager loads the entity relation, as the parameters need to be evaluated before calling the whenLoaded method:

$this->whenLoaded('entity', $this->resource->entity->comment),
                         // ^ HERE: as the parameter is evaluated, the entity relation is lazy-loaded

By using a closure, besides working around the issue introduced by PR #51342, you also prevent lazy-loading the entity relation.

[jeanroloff]

@rodrigopedra Im glad for the workaround you have provided, we were already aware of it
The eager/lazy loading is something that we were not aware though, and we will investigate it further, thanks for pointing that out
As of now, we have a large codebase that is affected by this bug and dont have the manpower to make such a huge refactor.