Building a Simple Web API with Vanilla PHP

This article is inspired by Brad Cypert's blog post: http://www.bradcypert.com/building-a-simple-api-in-php-using-lumen/.

Why should we build a API with Vanilla PHP? Because you can, and it makes fun.

Let's go

• Create a directory /src

• Create a file: src/functions.php

function router($httpMethods, $route, $callback, $exit = true)
{
    static $path = null;
    if ($path === null) {
        $path = parse_url($_SERVER['REQUEST_URI'])['path'];
        $scriptName = dirname(dirname($_SERVER['SCRIPT_NAME']));
        $scriptName = str_replace('\\', '/', $scriptName);
        $len = strlen($scriptName);
        if ($len > 0 && $scriptName !== '/') {
            $path = substr($path, $len);
        }
    }
    if (!in_array($_SERVER['REQUEST_METHOD'], (array) $httpMethods)) {
        return;
    }
    $matches = null;
    $regex = '/' . str_replace('/', '\/', $route) . '/';
    if (!preg_match_all($regex, $path, $matches)) {
        return;
    }
    if (empty($matches)) {
        $callback();
    } else {
        $params = array();
        foreach ($matches as $k => $v) {
            if (!is_numeric($k) && !isset($v[1])) {
                $params[$k] = $v[0];
            }
        }
        $callback($params);
    }
    if ($exit) {
        exit;
    }
}

• Create a file .htaccess in the project root directory.

RewriteEngine on
RewriteRule ^$ public/ [L]
RewriteRule (.*) public/$1 [L]

• Create a directory /public
• Create a file: public/.htaccess

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^ index.php [QSA,L]

• Create a file: public/index.php

<?php

require_once __DIR__ . '/../src/functions.php';

// Default index page
router('GET', '^/$', function() {
    echo '<a href="users">List users</a><br>';
});

// GET request to /users
router('GET', '^/users$', function() {
    echo '<a href="users/1000">Show user: 1000</a>';
});

// With named parameters
router('GET', '^/users/(?<id>\d+)$', function($params) {
    echo "You selected User-ID: ";
    var_dump($params);
});

// POST request to /users
router('POST', '^/users$', function() {
    header('Content-Type: application/json');
    $json = json_decode(file_get_contents('php://input'), true);
    echo json_encode(['result' => 1]);
});

header("HTTP/1.0 404 Not Found");
echo '404 Not Found';

Start the webserver

cd public
php -S localhost:8080

Open the browser: http://localhost:8080

Have fun :-)