Prepending component attributes causes an exception when said attribute is missing in calling template

[panda-madness]

• Laravel Version: 8.13
• PHP Version: 7.4
• Database Driver & Version: none

Description:

Rendering a component with prepended attributes but without overriding that attribute in the calling template yields an error.

Steps To Reproduce:

• composer create-project laravel/laravel testing
• php artisan make:component TestComponent
• Copy the example from the docs into the template

<div {{ $attributes->merge(['data-controller' => $attributes->prepends('profile-controller')]) }}>
    {{ $slot }}
</div>

• attempt to render the component without 'data-controller' specified.

Rendering this component like so: <x-test-component data-controller="some-controller" /> works as expected.

Rendering this component like so: <x-test-component /> yields the following error:

I would expect to have the string profile-controller to be the default and only value present if no attribute named data-controller is specified.

[panda-madness]

I've hotfixed this locally by adding a __toString method to AppendableAttributeValue like so:

<?php

namespace Illuminate\View;

class AppendableAttributeValue
{
    /**
     * The attribute value.
     *
     * @var mixed
     */
    public $value;

    /**
     * Create a new appendable attribute value.
     *
     * @param  mixed  $value
     * @return void
     */
    public function __construct($value)
    {
        $this->value = $value;
    }

    public function __toString()
    {
        return (string)$this->value;
    }
}

Not sure how this affects other parts of the code though.

[driesvints]

Copy the example from the docs into the template

Which example?

[panda-madness]

@driesvints the one from the Non-class attribute merging section. I've provided it verbatim in my original post.

[driesvints]

Copy paste your TestComponent please.

[panda-madness]

It's just an empty default Component stub:

<?php

namespace App\View\Components;

use Illuminate\View\Component;

class TestComponent extends Component
{
    /**
     * Create a new component instance.
     *
     * @return void
     */
    public function __construct()
    {
        //
    }

    /**
     * Get the view / contents that represent the component.
     *
     * @return \Illuminate\Contracts\View\View|string
     */
    public function render()
    {
        return view('components.test-component');
    }
}

[driesvints]

Thanks. I managed to reproduce this. I think the __toString solution is a valid one. Can you PR it? A test would be useful as well.

[panda-madness]

Sure, I'll link it here when it's ready.

[panda-madness]

Fixed in #35131