Slim 4 - Respect/Validation
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Daniel's Dev Blog
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Blog About me DonateSlim 4 - Respect/Validation
08 Oct 2020
Table of contents
Requirements
- PHP 7.3+
- A Slim 4 application
Introduction
The Respect/Validation component is a popular and flexible validation library for PHP.
It works as standalone libary and without much additional dependencies.
Installation
To install Respect/Validation, run:
composer require respect/validation
Usage
I think the most common use case is to validate nested arrays. For this reason I will show how to validate a simple array with this fields:
username: required, min. length is 3, the max. length is 60password: required, min. length is 8, the max. length is 60email: required, must be a valid email addressmobile: optional, must be a valid phone number
To fetch the form data as an array use this code in your action class:
$formData = (array)$request->getParsedBody();
Then pass this array into your service for validation. Within a service class you are able to perform the validation as follows:
use Respect\Validation\Validator as v;
// ...
$validator = new v();
$validator->addRule(v::key('username', v::allOf(
v::notEmpty()->setTemplate('The username must not be empty'),
v::length(3, 24)->setTemplate('Invalid length')
))->setTemplate('The key "username" is required'));
$validator->addRule(v::key('email', v::allOf(
v::notEmpty()->setTemplate('The email must not be empty'),
v::email()->setTemplate('Invalid email address')
))->setTemplate('The key "email" is required'));
$validator->addRule(v::key('password', v::allOf(
v::notEmpty()->setTemplate('The password must not be empty'),
v::length(8, 60)->setTemplate('Invalid length')
))->setTemplate('The key "password" is required'));
//...
Optional fields can be added like this. Just pass false to make the key optional:
$validator->addRule(v::key('mobile', v::allOf(
v::notEmpty()->setTemplate('The mobile number must not be empty'),
v::phone()->setTemplate('Invalid phone number')
), false));
To start the validation use the assert method.
$validator->assert($formData);
Translations
To translate the strings for the error messages, just use the _ or __ function of gettext.
$validator->addRule(v::key('username', v::allOf(
v::notEmpty()->setTemplate(__('The username must not be empty')),
v::length(3, 24)->setTemplate(__('Invalid length'))
))->setTemplate(__('The key %s is required', 'username'));
Validation Middleware
As soon as the validation fails a NestedValidationException will be thrown.
This is great, because you can transform this specific exception into an JSON response with status code 422.
For this purpose we add a custom middleware to the stack.
Create a new file src/middleware/RespectValidationMiddleware.php and copy / paste this content:
<?php
namespace App\Middleware;
use Psr\Http\Message\ResponseFactoryInterface;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;
use Respect\Validation\Exceptions\NestedValidationException;
final class RespectValidationMiddleware implements MiddlewareInterface
{
/**
* @var ResponseFactoryInterface
*/
private $responseFactory;
/**
* The constructor.
*
* @param ResponseFactoryInterface $responseFactory The response factory
*/
public function __construct(ResponseFactoryInterface $responseFactory)
{
$this->responseFactory = $responseFactory;
}
/**
* Invoke middleware.
*
* @param ServerRequestInterface $request The request
* @param RequestHandlerInterface $handler The handler
*
* @return ResponseInterface The response
*/
public function process(
ServerRequestInterface $request,
RequestHandlerInterface $handler
): ResponseInterface {
try {
return $handler->handle($request);
} catch(NestedValidationException $exception) {
$messages = [];
/** @var ValidationException $message */
foreach($exception->getIterator() as $message) {
$key = $message->getParam('name');
if($key === null) {
continue;
}
$messages[$key] = $message->getMessage();
}
$response = $this->responseFactory->createResponse();
$result = [
'error' => [
'message' => $exception->getMessage(),
'details' => $messages,
],
];
$response->getBody()->write(json_enode($result));
$response->withHeader('Content-Type', 'application/json');
return $response->withStatus(422);
}
}
}
In order to make it work, the RespectValidationMiddleware::class must be added after the Slim ErrorMiddleware:
<?php
use App\Middleware\RespectValidationMiddleware;
// ...
$app->addErrorMiddleware(true, true, true);
$app->add(RespectValidationMiddleware::class); // <-- here
Conclusion
The Respect/Validation component is very flexible and provides a lot of rules out of the box. It’s maintained and the download number on github is impressive.
A lot of magic is going on when you use the static method of the validator class. I prefer less magic and more rubust and faster code. For me a real fluent interface would be more readable and elegant, but this is just a matter of taste.
It was quite hard for me to find out how to add a custom message and translations to each validation rule. In the end it worked.
Read more
© 2020 Daniel Opitz | Twitter
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