Create a custom validation attribute

[savr-reda]

Hi,

The current documentation isn't very explicit regarding how to create custom validation attributes. I need to create a custom validation attribute that I could apply to my DTO properties, however, I could not find a proper way to achieve this.

I came across several issues and questions and tried several implementations (here and here for example), but there's no explicit answer to how to achieve something like this:

class Dog extends Data
{
    #[AllowedName] // Validation attribute with custom logic
    public string $name;
}

#[Attribute(Attribute::TARGET_PROPERTY)]
class AllowedName extends ValidationRule
{
    public function getRules(): array
    {
       // AllowedNameValidationRule implements Illuminate\Contracts\Validation\ValidationRule
        return [new AllowedNameValidationRule()];
    }
}

However I get:

PHP Error:  Object of class Rules\AllowedName could not be converted to string in /var/www/html/vendor/laravel/framework/src/Illuminate/Validation/ValidationRuleParser.php on line 134

Can you please provide some more explanation?

[rubenvanassche]

Yeah this was a bit difficult. I've added a new class + updated the docs on this, release normally later today.

[clementbirkle]

After searching for a while, I found the solution: the problem occurs when the rule doesn't implement the ValidationRule contract.

Here is an example of how to fix that:

<?php

namespace App\Rules;

use Attribute;
use Illuminate\Contracts\Validation\ValidationRule
use Spatie\LaravelData\Support\Validation\ValidationPath;
use Spatie\LaravelData\Attributes\Validation\CustomValidationAttribute;

#[Attribute(Attribute::TARGET_PROPERTY | Attribute::TARGET_PARAMETER)]
class CustomRule extends CustomValidationAttribute implements ValidationRule
{
    /**
     * @return array<object|string>|object|string
     */
    public function getRules(ValidationPath $path): array|object|string;
    {
        return new CustomRule();
    }
}