Validating Laravel requests using rule objects
Laravel comes with a multitude of ways to validate request parameters. For instance, you could use Illuminate\Http\Request’s validate method where you can specify all the fields that you would want to get validated inside controller’s action. You can do it like so.
<?php
namespace App\Http\Controllers;
use App\Http\Controllers\Controller;
use Illuminate\Http\Request;
class PostController extends Controller
{
/**
* Store a new blog post.
*
* @param Request $request
* @return Response
*/
public function store(Request $request)
{
$validatedData = $request->validate([
'title' => ['required' | 'unique:posts' | 'max:255'],
'body' => ['required'],
'author.name' => ['required'],
]);
// The blog post is valid...
}
}
As shown above, you could specify predefined validation rules (separated by pipes [|]) on request parameters. Apart from these predefined validation rules, you can also define you own rules using “rule objects”.
Custom Rule Objects
Rule objects are essentially classes that implements Illuminate\Contracts\Validation\Rule interface. A rule object contains two methods: passes and message. The passes method receives the attribute value and name, and should return true or false depending on whether the attribute value is valid or not. The message method should return the validation error message that should be used when validation fails.
Rule objects can be generated using make:rule Artisan command like so.
$ php artisan make:rule Titlecase
This will generate a Titlecase rule object in app/Rules directory.
Here’s how a typical rule object looks like.
<?php
namespace App\Rules;
use Illuminate\Contracts\Validation\Rule;
class Titlecase implements Rule
{
/**
* Determine if the validation rule passes.
*
* @param string $attribute
* @param mixed $value
* @return bool
*/
public function passes($attribute, $value)
{
return ucwords($value) === $value;
}
/**
* Get the validation error message.
*
* @return string
*/
public function message()
{
return 'Each word in :attribute must begin with a capital letter';
}
}
Once the rule has been defined, you may attach it to a validator by passing an instance of the rule object with your other validation rules like so.
use App\Rules\Titlecase;
$request->validate([
'name' => ['required', 'string', new Titlecase],
]);
And that’s how you can implement your own custom rule objects that validates requests according to your needs.
Bonus
There are libraries such as axiom that provides a set of reusable and useful Laravel validation rule objects such as StrongPassword, TelephoneNumber, MaxWords and so on. So, you don’t need to re-invent the wheel for common validation rules!
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