The Templating Component

Installation¶

You can install the component in 2 different ways:

• Install it via Composer (symfony/templating on Packagist);
• Use the official Git repository (https://github.com/symfony/Templating).

Usage¶

The PhpEngine class is the entry point of the component. It needs a template name parser (TemplateNameParserInterface) to convert a template name to a template reference (TemplateReferenceInterface). It also needs a template loader (LoaderInterface) which uses the template reference to actually find and load the template:

use SymfonyComponentTemplatingPhpEngine;
use SymfonyComponentTemplatingTemplateNameParser;
use SymfonyComponentTemplatingLoaderFilesystemLoader;

$loader = new FilesystemLoader(__DIR__.'/views/%name%');

$templating = new PhpEngine(new TemplateNameParser(), $loader);

echo $templating->render('hello.php', array('firstname' => 'Fabien'));

<!-- views/hello.php -->
Hello, <?php echo $firstname ?>!

The render() method parses the views/hello.php file and returns the output text. The second argument of render is an array of variables to use in the template. In this example, the result will be Hello, Fabien!.

The $view Variable¶

In all templates parsed by the PhpEngine, you get access to a mysterious variable called $view. That variable holds the current PhpEngine instance. That means you get access to a bunch of methods that make your life easier.

Including Templates¶

The best way to share a snippet of template code is to create a template that can then be included by other templates. As the $view variable is an instance of PhpEngine, you can use the render method (which was used to render the template originally) inside the template to render another template:

<?php $names = array('Fabien', ...) ?>
<?php foreach ($names as $name) : ?>
    <?php echo $view->render('hello.php', array('firstname' => $name)) ?>
<?php endforeach ?>

Global Variables¶

Sometimes, you need to set a variable which is available in all templates rendered by an engine (like the $app variable when using the Symfony framework). These variables can be set by using the addGlobal() method and they can be accessed in the template as normal variables:

$templating->addGlobal('ga_tracking', 'UA-xxxxx-x');

In a template:

<p>The google tracking code is: <?php echo $ga_tracking ?></p>

Output Escaping¶

When you render variables, you should probably escape them so that HTML or JavaScript code isn’t written out to your page. This will prevent things like XSS attacks. To do this, use the escape() method:

<?php echo $view->escape($firstname) ?>

By default, the escape() method assumes that the variable is outputted within an HTML context. The second argument lets you change the context. For example, to output something inside JavaScript, use the js context:

<?php echo $view->escape($var, 'js') ?>

The component comes with an HTML and JS escaper. You can register your own escaper using the setEscaper() method:

$templating->setEscaper('css', function ($value) {
    // ... all CSS escaping

    return $escapedValue;
});

Helpers¶

The Templating component can be easily extended via helpers. Helpers are PHP objects that provide features useful in a template context. The component has 2 built-in helpers:

• Assets Helper
• Slots Helper

Before you can use these helpers, you need to register them using set():

use SymfonyComponentTemplatingHelperAssetsHelper;
// ...

$templating->set(new AssetsHelper());

Creating a Custom Engine¶

Besides providing a PHP templating engine, you can also create your own engine using the Templating component. To do that, create a new class which implements the EngineInterface. This requires 3 method:

• render($name, array $parameters = array()) - Renders a template
• exists($name) - Checks if the template exists
• supports($name) - Checks if the given template can be handled by this engine.

Using Multiple Engines¶

It is possible to use multiple engines at the same time using the DelegatingEngine class. This class takes a list of engines and acts just like a normal templating engine. The only difference is that it delegates the calls to one of the other engines. To choose which one to use for the template, the EngineInterface::supports() method is used.

use AcmeTemplatingCustomEngine;
use SymfonyComponentTemplatingPhpEngine;
use SymfonyComponentTemplatingDelegatingEngine;

$templating = new DelegatingEngine(array(
    new PhpEngine(...),
    new CustomEngine(...),
));