Use callable class for Validation just like using closure

[ajcastro]

I propose a new additional syntax for class based validation to use the same format as using closures:

class LoremCheck {
  public function __invoke($attribute, $value, $fail)
  {
    if ($value === 'foo') {
      $fail("Lorem ipsum ...");
    }
    
    if ($value === 'bar') {
      $fail("Dolor sit amet ...");
    }
  }
}

Usage:

$validator = Validator::make($request->all(), [
    'title' => [
        'required',
        'max:255',
        new LoremCheck()
    ],
]);

[ajcastro]

Here's how I do it on my project

<?php

namespace App\Rules;

use Illuminate\Contracts\Validation\Rule as RuleContract;

abstract class BaseInvokableValidationRule implements RuleContract
{
    /**
     * Indicates if the validation callback failed.
     *
     * @var bool
     */
    public $failed = false;

    /**
     * The validation error message.
     *
     * @var string|null
     */
    public $message;

    /**
     * Determine if the validation rule passes.
     *
     * @param  string  $attribute
     * @param  mixed  $value
     * @return bool
     */
    public function passes($attribute, $value)
    {
        $this->failed = false;

        $this->__invoke($attribute, $value, function ($message) {
            $this->failed = true;

            $this->message = $message;
        });

        return !$this->failed;
    }

    /**
     * Get the validation error message.
     *
     * @return string
     */
    public function message()
    {
        return $this->message;
    }

    /**
     * Run the validation
     *
     * @param string $attribute
     * @param mixed $value
     * @param callback $fail
     * @return void
     */
    abstract public function __invoke($attribute, $value, $fail);
}