Using View Helper for Accessing zend-expressive-flash Messages in Expressive 3

If you already tried zend-expressive 3.0.0alpha3, and want to use flash message for it, you can use the new component: “zendframework/zend-expressive-flash”.

Setup

We need to require the component and its dependencies:

$ composer require
    zendframework/zend-expressive-session:^1.0.0alpha1 \
    zendframework/zend-expressive-session-ext:^0.1.2 \
    zendframework/zend-expressive-flash:^1.0.0alpha1

After it, we can ensure that the ConfigProvider for above components registered at config/config.php:

$aggregator = new ConfigAggregator([
    // ...
    \Zend\Expressive\Session\ConfigProvider::class,
    \Zend\Expressive\Session\Ext\ConfigProvider::class,
    \Zend\Expressive\Flash\ConfigProvider::class,
    // ...
]);

To make the flash messages available in all pages, we need to register it in the pipeline before RouteMiddleware piping:

use Zend\Expressive\Flash\FlashMessageMiddleware;
use Zend\Expressive\Session\SessionMiddleware;
// ...

    $app->pipe(SessionMiddleware::class);
    $app->pipe(FlashMessageMiddleware::class);

    $app->pipe(RouteMiddleware::class);

Get the Messages via View Helper

Most of the use cases, we are displaying the flash messages in the layout. If we are using zend-view for the template engine, we can create view helper to access the flash messages. What we need is a Zend\Expressive\Flash\FlashMessages instance with passes Zend\Expressive\Session\Session which passes $_SESSION into it, as follows:

use Zend\Expressive\Session\Session;
use Zend\Expressive\Flash\FlashMessages;

// ...
$flashMessages = FlashMessages::createFromSession(new Session($_SESSION));

The messages is a private property “currentMessages” which currently no public function that returns it. We can wait for the PR for it to be merge or use it via ReflectionProperty or Closure.

If we are going to use Closure, we can do:

$closure = Closure::bind(function (FlashMessages $flashMessages) {
    return $flashMessages->currentMessages;
}, null, FlashMessages::class);

$closure($flashMessages);

Knowing that, we can create the view helper as follows:

<?php
// src/App/View\Helper\Flash.php

declare(strict_types=1);

namespace App\View\Helper;

use Closure;
use Zend\Expressive\Session\Session;
use Zend\Expressive\Flash\FlashMessages;
use Zend\View\Helper\AbstractHelper;

class Flash extends AbstractHelper
{
    public function __invoke() : array
    {
        $flashMessages = FlashMessages::createFromSession(
            new Session($_SESSION)
        );

        $closure = Closure::bind(function (FlashMessages $flashMessages) {
            return $flashMessages->currentMessages;
        }, null, FlashMessages::class);

        return $closure($flashMessages);
    }
}

and register it into view_helpers config at src/App/ConfigProvider::__invoke():

// ...
    public function __invoke() : array
    {
        return [
            'dependencies' => $this->getDependencies(),
            'templates'    => $this->getTemplates(),

            // register additional view helpers
            'view_helpers' => [
                'invokables' => [
                    'flash' => View\Helper\Flash::class,
                ],
            ],
        ];
    }
// ...

Accessing Flash Messages in Layout

In layout, we can now access it via invoked flash view helper with loop the messages to be displayed:

<?php if ($flashes = $this->flash()) :?>
    <ul>
        <?php foreach($flashes as $message) : ?>
            <li><?php echo $message; ?></li>
        <?php endforeach; ?>
    </ul>
<?php endif; ?>

Give it a try

You can now create a flash messages in some page and access it in next request in the layout, check the documentation for its usage!

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