Do you remember the only rule for a controller? It must return a Symfony Response object! But Symfony doesn't care how you do that: you could render a template, make API requests or make database queries and build a JSON response.


Technically, a controller can return anything. Eventually, you'll learn how and why to do this.

Really, most of learning Symfony involves learning to install and use a bunch of powerful, but optional, tools that make this work easier. If your app needs to return HTML, then one of these great tools is called Twig.

Installing Twig

First, make sure you commit all of your changes so far:

git status

I already did this. Recipes are so much more fun when you can see what they do! Now run:

composer require twig

By the way, in future tutorials, our app will become a mixture of a traditional HTML app and an API with a JavaScript front-end. So if you want to know about building an API in Symfony, we'll get there!

This installs TwigBundle, a few other libraries and... configures a recipe! What did that recipe do? Let's find out:

git status

Woh! Lot's of good stuff! The first change is config/bundles.php:

9 lines config/bundles.php
... lines 1 - 2
return [
... lines 4 - 6
Symfony\Bundle\TwigBundle\TwigBundle::class => ['all' => true],

Bundles are the "plugin" system for Symfony. And whenever we install a third-party bundle, Flex adds it here so that it's used automatically. Thanks Flex!

The recipe also created some stuff, like a templates/ directory! Yep, no need to guess where templates go: it's pretty obvious! It even added a base layout file that we'll use soon.

Twig also needs some configuration, so the recipe added it in config/packages/twig.yaml:

5 lines config/packages/twig.yaml
paths: ['%kernel.project_dir%/templates']
debug: '%kernel.debug%'
strict_variables: '%kernel.debug%'

But even though this file was added by Flex, it's yours to modify: you can make whatever changes you want.

Oh, and I love this! Why do our templates need to live in a templates/ directory. Is that hardcoded deep inside Symfony? Nope! It's right here!

5 lines config/packages/twig.yaml
paths: ['%kernel.project_dir%/templates']
... lines 3 - 5

Don't worry about this percent syntax yet - you'll learn about that in a future episode. But, you can probably guess what's going on: %kernel.project_dir% is a variable that points to the root of the project.

Anyways, looking at what a recipe did is a great way to learn! But the main lesson of Flex is this: install a library and it takes care of the rest.

Now, let's go use Twig!

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