The Ultimate Guide to Laravel Validation

Laravel, a popular PHP framework, provides a robust validation mechanism to ensure the integrity of incoming data. This guide will walk you through the essentials of Laravel validation, covering various aspects including basic validation, custom validation rules, error handling, and more.

1. Basic Validation

Validating Requests

To validate an incoming HTTP request, you can use the validate method provided by Laravel. This method is often called in a controller.

public function store(Request $request)
{
    $validatedData = $request->validate([
        'name' => 'required|max:255',
        'email' => 'required|email|unique:users',
        'password' => 'required|min:8',
    ]);

    // The validated data can be used safely
}

Available Validation Rules

Laravel offers a wide range of validation rules, including but not limited to:

required: The field under validation must be present and not empty.
email: The field under validation must be formatted as an email address.
unique:table,column: Ensures the value is unique in a specific database table and column.
max:value: The field under validation must have a maximum value.

For a comprehensive list, refer to the official documentation.

2. Custom Validation Messages

You can customize the validation error messages by passing an array as the third parameter to the validate method.

public function store(Request $request)
{
    $validatedData = $request->validate([
        'name' => 'required|max:255',
        'email' => 'required|email|unique:users',
        'password' => 'required|min:8',
    ], [
        'name.required' => 'The name field is required.',
        'email.required' => 'We need to know your email address!',
        'password.required' => 'Please enter a password.',
    ]);

    // Process the validated data
}

3. Form Request Validation

For more complex validation logic, you can use Form Request classes. These classes encapsulate the validation logic and authorization.

Creating a Form Request

Generate a Form Request class using Artisan:

php artisan make:request StoreUserRequest

Using the Form Request

Within the StoreUserRequest class, you define the validation rules and custom messages.


namespace App\Http\Requests;

use Illuminate\Foundation\Http\FormRequest;

class StoreUserRequest extends FormRequest
{
    public function authorize()
    {
        return true;
    }

    public function rules()
    {
        return [
            'name' => 'required|max:255',
            'email' => 'required|email|unique:users',
            'password' => 'required|min:8',
        ];
    }

    public function messages()
    {
        return [
            'name.required' => 'The name field is required.',
            'email.required' => 'We need to know your email address!',
            'password.required' => 'Please enter a password.',
        ];
    }
}

Use the StoreUserRequest in your controller:


public function store(StoreUserRequest $request)
{
    // The incoming request is valid...
    $validated = $request->validated();

    // Process the validated data
}

4. Custom Validation Rules

Laravel allows you to create custom validation rules if the built-in ones do not suffice.

Creating a Custom Rule

Generate a custom rule using Artisan:


php artisan make:rule Uppercase

Defining the Custom Rule

Within the generated rule class, define the validation logic:


namespace App\Rules;

use Illuminate\Contracts\Validation\Rule;

class Uppercase implements Rule
{
    public function passes($attribute, $value)
    {
        return strtoupper($value) === $value;
    }

    public function message()
    {
        return 'The :attribute must be uppercase.';
    }
}

Using the Custom Rule

Apply the custom rule in your controller or Form Request:


use App\Rules\Uppercase;

public function store(Request $request)
{
    $validatedData = $request->validate([
        'name' => ['required', 'max:255', new Uppercase],
    ]);

    // Process the validated data
}

5. Error Handling

Laravel provides a convenient way to handle validation errors. By default, it returns a 422 HTTP response with a JSON object containing the validation errors.

Accessing Validation Errors

In your Blade views, you can display validation errors using the $errors variable.


@if ($errors->any())
    <div class="alert alert-danger">
        <ul>
            @foreach ($errors->all() as $error)
                <li>{{ $error }}</li>
            @endforeach
        </ul>
    </div>
@endif

Redirecting with Errors

Laravel automatically redirects the user back to the previous page with validation errors and input data if validation fails.

6. Conditional Validation

You can apply validation rules conditionally using the sometimes method or within a closure.


$request->validate([
    'email' => 'required|email',
    'password' => 'required|min:8',
], [
    'email.required' => 'We need to know your email address!',
]);

$request->validate([
    'state' => 'required_if:country,US',
]);

7. Validation and Authorization

You can combine validation with authorization logic in Form Request classes. The authorize method determines if the user is authorized to make the request.


public function authorize()
{
    return auth()->user()->isAdmin();
}

Conclusion

Laravel's validation system is powerful and flexible, allowing you to ensure the integrity of incoming data with ease. Whether you use basic validation, Form Requests, or custom rules, Laravel provides the tools needed to validate and sanitize your data effectively. For more details and advanced usage, refer to the official Laravel documentation.

The Ultimate Guide to Laravel Validation