Using Latte with Slim 4

This article written by Daniel Opitz describes how to use Latte with the Slim Framework.

First, install the Slim Framework and then Latte using Composer:

composer require latte/latte

Configuration

Create a new directory templates in your project root directory. All templates will be placed there later.

Add a new template configuration key in your config/defaults.php file:

$settings['template'] = __DIR__ . '/../templates';

Latte compiles the templates to native PHP code and stores them in a cache on the disk. So they are as fast as if they had been written in native PHP.

Add a new template_temp configuration key in your config/defaults.php file: Make sure the directory {project}/tmp/templates exists and has read and write access permissions.

$settings['template_temp'] = __DIR__ . '/../tmp/templates';

Latte automatically regenerates the cache every time you change the template, which can be turned off in the production environment to save a little performance:

// change to false in the production environment
$settings['template_auto_refresh'] = true;

Next, add a DI container definitions for the Latte\Engine class.

<?php

use Latte\Engine;
use Latte\Loaders\FileLoader;
use Psr\Container\ContainerInterface;
// ...

return [

    // ...

    Engine::class => function (ContainerInterface $container) {
        $latte = new Engine();
        $settings = $container->get('settings');
        $latte->setLoader(new FileLoader($settings['template']));
        $latte->setTempDirectory($settings['template_temp']);
        $latte->setAutoRefresh($settings['template_auto_refresh']);

        return $latte;
    },
];

This alone would technically work to render a Latte template, but we also need to make it work with the PSR-7 response object.

For this purpose we create a special TemplateRenderer class which does this work for us.

So next create a file in src/Renderer/TemplateRenderer.php and copy/paste this code:

<?php

namespace App\Renderer;

use Latte\Engine;
use Psr\Http\Message\ResponseInterface;

final class TemplateRenderer
{
    private Engine $engine;

    public function __construct(Engine $engine)
    {
        $this->engine = $engine;
    }

    public function template(
        ResponseInterface $response,
        string $template,
        array $data = []
    ): ResponseInterface {
        $string = $this->engine->renderToString($template, $data);
        $response->getBody()->write($string);

        return $response;
    }
}

Usage

Instead of using the Latte Engine object directly we use the TemplateRenderer object to render the template into a PSR-7 compatible object.

A typical Action handler class might look like this to render a template with the name home.latte:

<?php

namespace App\Action\Home;

use App\Renderer\TemplateRenderer;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;

final class HomeAction
{
    private TemplateRenderer $renderer;

    public function __construct(TemplateRenderer $renderer)
    {
        $this->renderer = $renderer;
    }

    public function __invoke(
        ServerRequestInterface $request,
        ResponseInterface $response
    ): ResponseInterface {
        $viewData = [
            'items' => ['one', 'two', 'three'],
        ];

        return $this->renderer->template($response, 'home.latte', $viewData);
    }
}

To make it work, create a template file in templates/home.latte with this content:

<ul n:if="$items">
    {foreach $items as $item}
        <li id="item-{$iterator->counter}">{$item|capitalize}</li>
    {/foreach}
</ul>

If everything is configured correctly you should see the following output:

One
Two
Three