Flash Message Middleware
In order to provide flash messages to your middleware, you will first need to
register Mezzio\Flash\FlashMessageMiddleware
in your application
pipeline or routed middleware pipeline; additionally, you'll need to ensure
Mezzio\Session\SessionMiddleware
is registered prior to it.
This middleware does the following:
- Pulls the session container from the request via the attribute
Mezzio\Session\SessionMiddleware::SESSION_ATTRIBUTE
("session"). - Passes the container, along with a defined session key, to a factory for
generating a
FlashMessagesInterface
instance. - Passes that instance to a request that the delegate processes, using another request attribute.
Default configuration
By default, FlashMessageMiddleware
uses FlashMessages::createFromSession()
to generate the flash messages container, the key
Mezzio\Flash\FlashMessagesInterface::FLASH_NEXT
(this is a literal
string) to pull stored flash messages from the session, and the request
attribute FlashMessageMiddleware::FLASH_ATTRIBUTE
("flash") to pass the flash
messages container to the next middleware.
If you are using the laminas-component-installer Composer plugin, the middleware will already be wired for you. Otherwise, you will need to map the middleware to your dependency injection container as an invokable (no constructor arguments).
If these defaults will work for you, you have no further configuration to do.
Custom configuration
If you want to specify a different flash messages container implementation, a
different session key, or a different flash messages request attribute name, you
will need to create a new factory for your FlashMessagesMiddleware
. As an
example, in the following, I specify:
Application\FlashMessages
as the flash messages container; this class will need to implementFlashMessagesInterface
, including the static methodcreateFromSession()
.- The string
Application\FlashMessages::FLASH_NEXT
as the session key in which flash messages will be stored. - The request attribute
flash-messages
in which to store the flash messages container.
use Application\FlashMessages;
use Psr\Container\ContainerInterface;
use Mezzio\Flash\FlashMessageMiddleware;
class FlashMessageMiddlewareFactory
{
public function __invoke(ContainerInterface $container)
{
return new FlashMessageMiddleware(
FlashMessages::class,
FlashMessages::class . '::FLASH_NEXT',
'flash-messages'
);
}
}
Once you have created this factory, map the FlashMessageMiddleware
to it in
your dependency injection configuration:
'dependencies' => [
'factories' => [
\Mezzio\Flash\FlashMessageMiddleware::class => FlashMessageMiddlewareFactory::class,
],
],
Piping the middleware
You may pipe this middleware either in your application pipeline
(config/pipeline.php
) or a routed middleware pipeline (config/routes.php
, or
a delegator factory). When you do, you MUST register it AFTER the
Mezzio\Session\SessionMiddleware
as it depends on that middleware for
its session container.
As an example within an application pipeline:
$app->pipe(\Mezzio\Session\SessionMiddleware::class);
$app->pipe(\Mezzio\Flash\FlashMessageMiddleware::class);
Within a routed middleware definition:
$app->post('/user/login', [
\Mezzio\Session\SessionMiddleware::class,
\Mezzio\Flash\FlashMessageMiddleware::class,
LoginHandler::class,
]);