how do flash message with Slim framework 3 - php

Question

I have the problem to use Slim/Flash/Messages, to do a flash message. I have this error
Fatal error:
Uncaught DI\NotFoundException: No entry or class found for 'Slim\Flash' in C:\laragon\www\cart\vendor\php-di\php-di\src\DI\Container.php:119
Stack trace:
#0 C:\laragon\www\cart\app\container.php(52): DI\Container->get('Slim\\Flash')
#1 [internal function]: DI\Definition\Source\DefinitionFile->{closure}(Object(DI\Container)) #2 C:\laragon\www\cart\vendor\php-di\invoker\src\Invoker.php(82): call_user_func_array(Object(Closure), Array)
#3 C:\laragon\www\cart\vendor\php-di\php-di\src\DI\Definition\Resolver\FactoryResolver.php(81): Invoker\Invoker->call(Object(Closure), Array)
#4 C:\laragon\www\cart\vendor\php-di\php-di\src\DI\Definition\Resolver\ResolverDispatcher.php(58): DI\Definition\Resolver\FactoryResolver->resolve(Object(DI\Definition\FactoryDefinition), Array)
#5 C:\laragon\www\cart\vendor\php-di\php-di\src\DI\Container.php(285): DI\Definition\Resolver\ResolverDispatcher->resolve(Object(DI\Definition\FactoryDefinition), Array)
#6 C:\laragon\www\cart\vendor\php-di\php-di\src\DI\Container.php(122): DI\Contai in C:\laragon\www\cart\vendor\php-di\php-di\src\DI\Container.php on line 119
In the bootstrap/app.php
$container->set('flash', function($container) {
return new \Slim\Flash\Messages($container);
});
in the container.php
Twig::class => function (ContainerInterface $c) {
$twig = Factory::getEngine();
$twig->addExtension(new TwigExtension(
$c->get('router'),
$c->get('request')->getUri()
));
$twig->getEnvironment()->addGlobal('basket', $c->get(Basket::class));
$twig->getEnvironment()->addGlobal('auth', $c->get(Auth::class));
$twig->getEnvironment()->addGlobal('user', $c->get(Customer::class));
$twig->getEnvironment()->addGlobal('flash', $c->get(Flash::class));
return $twig;
},

Answer 1

$twig->getEnvironment()->addGlobal('flash', $c->get(Flash::class)); means that you're looking for a key called Slim\Flash within the container, but you registered it with the key flash.
Therefore change:
$twig->getEnvironment()->addGlobal('flash', $c->get(Flash::class));
to
$twig->getEnvironment()->addGlobal('flash', $c->get('flash'));
Alternatively, you can use the fully qualified class name everywhere:
app.php:
use Slim\Flash\Messages as Flash;
$container->set(Flash::class, function($container) {
return new Flash($container);
});
and add this to the top of container.php:
use Slim\Flash\Messages as Flash;