<?php

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\ParameterBag;

// Assume querystring = /path/of/route?foo=text&bar=anothertext2&qux=100
$request = new Request();

/** @var ParameterBag $parameterBag */
$parameterBag = $request->query;

dump(
    $parameterBag->keys(),
    $parameterBag->has('foo'),
    $parameterBag->get('qux'),
    $parameterBag->getBoolean('qux'),
    $parameterBag->getAlpha('bar'),
    $parameterBag->getDigits('bar'),
    $parameterBag->getInt('bar'),
    // returns false if value doesn't fit to filter
    $parameterBag->filter('bar', null, FILTER_VALIDATE_INT, ['options' => ['default' => 1]]),
    $parameterBag->filter('qux', 1, FILTER_VALIDATE_INT),
    count($parameterBag)
);

array:3 [

  0 => "foo"

  1 => "bar"

  2 => "qux"

]

true

100

false

"anothertext"

"2"

0

1

100

3

• Using an object in ExpressionLanguage
• Simple Symfony Session
• The basics of Symfony EventDispatcher

PHP 7.2, Zend 3.0, Symfony 4.0, Laravel 5.6, PHPUnit 6.5, Doctrine 2.8