Create Reusable Custom Validation Rules in Laravel

Laravel allows you to create custom validation rules when built-in validation isn't enough. Instead of repeating complex validation logic across multiple Form Requests, you can encapsulate it into a reusable rule class.

Create a Rule

Generate a new validation rule using Artisan:

php artisan make:rule UsernameRule

Laravel creates a new rule class inside:

app/Rules/UsernameRule.php

Define the Validation Logic

use Closure;
use Illuminate\Contracts\Validation\ValidationRule;
class UsernameRule implements ValidationRule
{
    public function validate(string $attribute,
        mixed $value,
        Closure $fail): void {
        if (in_array(strtolower($value), [
            'admin',
            'root',
            'support',
        ])) {
            $fail('This username is reserved.');
        }
    }
}

Use the Rule

use App\Rules\UsernameRule;
public function rules(): array
{
    return [
        'username' => [
            'required',
            new UsernameRule(),
        ],
    ];
}

That's it! The rule can now be reused anywhere in your application.

Why Use Custom Validation?

Custom validation rules help you:

• Reuse validation logic
• Keep Form Requests concise
• Centralize business rules
• Improve code readability
• Simplify testing

When Should You Create a Custom Rule?

Create one when:

• Validation is used in multiple places
• Business rules are more complex than built-in validators
• You want cleaner and more maintainable code