Request + Routing - Minimalist zero-dependency PHP solution for JSON handling. Useful for development, not suited for production.

1_Request-JSON-Data.php

<?php

declare(strict_types=1);

namespace App;

use Exception;

use function addslashes;
use function file_get_contents;
use function header;
use function htmlspecialchars;
use function is_array;
use function is_string;
use function json_decode;
use function json_encode;
use function trim;

use const ENT_QUOTES;

/**
 * HTTP request handling.
 */
// phpcs:ignore
abstract class Request
{
    /**
     * API method name to match to functionality.
     *
     * @var null|string
     */
    protected $method;

    public function __construct()
    {
        $this->method = $this->getRequestMethodName();
    }

    /**
     * Get input data from request as JSON.
     *
     * @todo Optimize - Check if security measures are needed
     */
    public function getInputAsJson(): array
    {
        $input = file_get_contents('php://input');
        $data  = json_decode($input, true);

        if (!$data || !is_array($data)) {
            throw new Exception('Input is invalid JSON');
        }

        return $data;
    }

    /**
     * Output data as JSON.
     */
    public function showAsJson(array $data)
    {
        header('Content-Type: application/json; charset=utf-8');

        echo json_encode($data);
    }

    /**
     * Get requested API method name.
     */
    private function getRequestMethodName(): string
    {
        $raw = $_REQUEST['method'] ?? '';

        if (!is_string($raw)) {
            return '';
        }

        $name = empty($raw) ? '' : $raw;
        $name = trim($raw);
        $name = htmlspecialchars($raw, ENT_QUOTES);
        $name = addslashes($raw);

        return $name;
    }
}

2_Query-Handling-Example.php

<?php

declare(strict_types=1);

namespace App;

use Exception;

/**
 * API method handling from routes.
 */
// phpcs:ignore
final class RequestRoutes extends Request
{
    /**
     * Database queries instance.
     *
     * @var null|object
     */
    private $dbQueries;

    /**
     * Constructor initializes request and sets dependencies.
     */
    public function __construct(/* DatabaseQueries */ $dbQueries)
    {
        parent::__construct();

        $this->dbQueries = $dbQueries;
    }

    /**
     * Route API URLs to corresponding functions or throw error.
     *
     * @throws Exception
     */
    public function route()
    {
        switch ($this->method) {
            case "price":
                $this->handleTotalPrice();
                break;
            case "products":
                $this->handleProductPost();
                break;
            default:
                throw new Exception("Method '$this->method' does not correspond to API functionality.");
        }
    }

    /**
     * @todo WIP - Implement feature
     */
    private function handleTotalPrice()
    {
        $price = $this->dbQueries
            ->start()
            ->getTotalPrice();

        $this->showAsJson(['sum' => $price]);
    }

    /**
     * Save products to database.
     * Get from input, save and output status result.
     *
     * @todo Optimize - Implement checking for $_POST request and deny others.
     * @todo Concept - Decide on return values for errors.
     * @todo Concept - Check for additionally required security measures.
     * @throws Exception
     */
    private function handleProductPost()
    {
        $productData = $this->getInputAsJson();

        $this->dbQueries
            ->start()
            ->saveOrder($productData);

        $this->showAsJson(['success' => true]);
    }
}