Converting a GET parameter to a bool type with PHP

Published on 2023-09-01 • Modified on 2023-09-01

This snippet shows how to convert a GET parameter to a bool type with PHP. Sometimes, when you need to convert a GET filter on an API endpoint, you need to transform this parameter into a boolean variable: true or false. You could use a bool cast, but this can have unexpected results. For example, (bool) "false", returns true, not false. To address this problem, we can use the filter_var function with the FILTER_VALIDATE_BOOLEAN flag.

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<?php

declare(strict_types=1);

// src/Controller/Snippet/Snippet268Trait.php

namespace App\Controller\Snippet;

use Symfony\Component\HttpFoundation\Request;

/**
 * I am using a PHP trait to isolate each snippet in a file.
 * This code should be called from a Symfony controller extending AbstractController (as of Symfony 4.2)
 * or Symfony\Bundle\FrameworkBundle\Controller\Controller (Symfony <= 4.1).
 * Services are injected in the main controller constructor.
 */
trait Snippet268Trait
{
    public function snippet268(Request $request): void
    {
        $values = [
            // true
            'on',
            'true',
            '1',
            'yes',
            1,
            true,

            // false
            'off',
            'false',
            '0',
            'no',
            'foo',
            [],
            0,
            false,
            null,
        ];

        foreach ($values as $value) {
            var_dump($value);
            var_dump(filter_var($value, FILTER_VALIDATE_BOOL));
            echo PHP_EOL;
        }

        // That's it! 😁
    }
}

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