10 Serving JSON

Goal

Combine everything from this tier into the artifact it's been building toward: a small JSON HTTP API served by PHP's built-in server, with no framework and no third-party dependency.

Prerequisites

• Hello HTTP, JSON Encoding

The API

Two routes:

• GET /items — returns the full item list as a JSON array
• GET /items/{id} — returns a single item by index, or a 404 if out of range

Code

Create router.php:

<?php

header('Content-Type: application/json');

class Item {
    public function __construct(
        public readonly string $name,
        public readonly float $price,
    ) {}
}

$items = [
    new Item("Widget", 9.99),
    new Item("Gadget", 19.99),
    new Item("Gizmo", 29.99),
];

$path = $_SERVER['REQUEST_URI'];

if ($path === '/items') {
    echo json_encode($items);
    exit;
}

if (preg_match('#^/items/(\d+)$#', $path, $matches)) {
    $id = (int) $matches[1];

    if (!isset($items[$id])) {
        http_response_code(404);
        echo json_encode(["error" => "item not found"]);
        exit;
    }

    echo json_encode($items[$id]);
    exit;
}

http_response_code(404);
echo json_encode(["error" => "not found"]);

header('Content-Type: application/json') sets the response header — without it, browsers and some HTTP clients treat the response as plain text instead of JSON. preg_match with the #^/items/(\d+)$# pattern extracts a numeric ID from paths like /items/1; $matches[1] holds the captured digits.

Run It

php -S localhost:8000 router.php

In a second terminal:

curl http://localhost:8000/items

[{"name":"Widget","price":9.99},{"name":"Gadget","price":19.99},{"name":"Gizmo","price":29.99}]

curl http://localhost:8000/items/1

{"name":"Gadget","price":19.99}

curl -i http://localhost:8000/items/99

HTTP/1.1 404 Not Found
...
{"error":"item not found"}

Stop the server with Ctrl-C.

Checkpoint

All three responses above should match. This is the artifact the Intermediate tier picks up next — swapping the hardcoded $items array for real persistence (PDO, SQLite or MySQL) without changing the routing shape.

What's Next

The Beginner tier's page ladder ends here. Intermediate continues this same artifact with a persistence layer.