การใช้งาน Container ร่วมกับ Slim framework 4

composer require league/container

// สร้าง Container โดยใช้ League Container
$container = new League\Container\Container();

// กำหนดการใช้ Container สำหรับร่วมกับการสร้าง app
Slim\Factory\AppFactory::setContainer($container);
$app = AppFactory::create();

// กำหนด service ให้กับ container
$container->add('db', function () {
    $mysqli = new mysqli("localhost", "root","","test");  
    if ($mysqli->connect_errno) exit();
    if (!$mysqli->set_charset("utf8")) exit();  
    return $mysqli;
});

$app->get('/home', function (Request $request, Response $response, $args) {  
    $db = $this->get('db');
    $response->getBody()->write('Welcome');   
    return $response;
});

$app->get('/home', function (Request $request, Response $response, $args) {  
    if ($this->has('db')) {
        $db = $this->get('db');
    }
    $response->getBody()->write('Welcome');   
    return $response;
});

<?php
use Psr\Http\Message\ResponseInterface as Response;
use Psr\Http\Message\ServerRequestInterface as Request;
use Slim\Factory\AppFactory;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Log\LoggerInterface;

require __DIR__ . '/./vendor/autoload.php';

// สร้าง Container โดยใช้ League Container
$container = new League\Container\Container();

// กำหนดการใช้ Container สำหรับร่วมกับการสร้าง app
Slim\Factory\AppFactory::setContainer($container);
$app = AppFactory::create();
$app->setBasePath('/demo/api');

// กำหนด service ให้กับ container
$container->add('db', function () {
    $mysqli = new mysqli("localhost", "root","","test");  
    if ($mysqli->connect_errno) exit();
    if (!$mysqli->set_charset("utf8")) exit();  
    return $mysqli;
});


// กำหนดรุปแบบ Error Handler เอง
$customErrorHandler = function (
    ServerRequestInterface $request,
    Throwable $exception,
    bool $displayErrorDetails,
    bool $logErrors,
    bool $logErrorDetails,
    ?LoggerInterface $logger = null
) use ($app) {

    $payload = ['error' => $exception->getMessage()];

    $response = $app->getResponseFactory()->createResponse();
    $response->getBody()->write(
        json_encode($payload, JSON_UNESCAPED_UNICODE)
    );
    return $response
              ->withHeader('Content-Type', 'application/json');
};
// Error Middleware
$errorMiddleware = $app->addErrorMiddleware(false, true, true);
$errorMiddleware->setDefaultErrorHandler($customErrorHandler); // เรียกใช้งานรูปแบบที่กำหนด


// Routing
$app->get('/province[/{id:[[:digit:]]+}]', function (Request $request, Response $response, $args) {
    $data = [];
    if ($this->has('db')) {
        $db = $this->get('db');
        $sql = "
        SELECT * FROM tbl_provinces WHERE 1 
        ";
        if(isset($args['id'])){ // ถ้าระบุ id จังหวัด
            $sql.= " AND province_id='".(int)$args['id']."' ";
        }
        $result = $db->query($sql);
        if( $result && $result->num_rows > 0 ){
            $data = $result->fetch_all(MYSQLI_ASSOC);
        }
    }
    $payload = json_encode($data);
 
    $response->getBody()->write($payload);
    return $response
              ->withHeader('Content-Type', 'application/json');
});


$app->run();