Create your First Page in Symfony

Create your First Page in Symfony

Creating a new page - whether it's an HTML page or a JSON endpoint - is a simple two-step process:

  1. Create a route: A route is the URL (e.g. /about) to your page and points to a controller;
  2. Create a controller: A controller is the PHP function you write that builds the page. You take the incoming request information and use it to create a Symfony Response object, which can hold HTML content, a JSON string or even a binary file like an image or PDF.
Do you prefer video tutorials? Check out the Joyful Development with Symfony screencast series from KnpUniversity.
Symfony embraces the HTTP Request-Response lifecycle. To find out more, see Symfony and HTTP Fundamentals.

Creating a Page: Route and Controller

Tip

Before continuing, make sure you've read the Setup chapter and can access your new Symfony app in the browser.

Suppose you want to create a page - /lucky/number - that generates a lucky (well, random) number and prints it. To do that, create a "Controller class" and a "controller" method inside of it that will be executed when someone goes to /lucky/number:

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// src/AppBundle/Controller/LuckyController.php
namespace AppBundle\Controller;

use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Symfony\Component\HttpFoundation\Response;

class LuckyController
{
    /**
     * @Route("/lucky/number")
     */
    public function numberAction()
    {
        $number = mt_rand(0, 100);

        return new Response(
            '<html><body>Lucky number: '.$number.'</body></html>'
        );
    }
}

Before diving into this, test it out! If you are using PHP's internal web server go to:

Tip

If you're using the built-in PHP web-server, you can omit the app_dev.php part of the URL.

If you see a lucky number being printed back to you, congratulations! But before you run off to play the lottery, check out how this works. Remember the two steps to creating a page?

  1. Create a route: The @Route above numberAction() is the route: it defines the URL pattern for this page. You'll learn more about routing in its own section, including how to make variable URLs;
  2. Create a controller: The method below the route - numberAction() - is called the controller: this is a function where you build the page and ultimately return a Response object. You'll learn more about controllers in their own section, including how to return JSON responses;

The Web Debug Toolbar: Debugging Dream

If your page is working, then you should also see a bar along the bottom of your browser. This is called the Web Debug Toolbar: and it's your debugging best friend. You'll learn more about all the information it holds along the way, but feel free to experiment: hover over and click the different icons to get information about routing, performance, logging and more.

Rendering a Template (with the Service Container)

If you're returning HTML from your controller, you'll probably want to render a template. Fortunately, Symfony comes with Twig: a templating language that's easy, powerful and actually quite fun.

First, make sure that LuckyController extends Symfony's base Controller class:

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// src/AppBundle/Controller/LuckyController.php

// ...
// --> add this new use statement
use Symfony\Bundle\FrameworkBundle\Controller\Controller;

class LuckyController extends Controller
{
    // ...
}

Now, use the handy render() function to render a template. Pass it our number variable so we can render that:

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// src/AppBundle/Controller/LuckyController.php

// ...
class LuckyController extends Controller
{
    /**
     * @Route("/lucky/number")
     */
    public function numberAction()
    {
        $number = mt_rand(0, 100);

        return $this->render('lucky/number.html.twig', array(
            'number' => $number
        ));
    }
}

Finally, template files should live in the app/Resources/view directory. Create a new app/Resources/views/lucky directory with a new number.html.twig file inside:

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{# app/Resources/views/lucky/number.html.twig #}

<h1>Your lucky number is {{ number }}</h1>

The {{ number }} syntax is used to print variables in Twig. Refresh your browser to get your new lucky number!

In the Creating and Using Templates chapter, you'll learn all about Twig: how to loop, render other templates and leverage its powerful layout inheritance system.

Checking out the Project Structure

Great news! You've already worked inside the two most important directories in your project:

app/
Contains things like configuration and templates. Basically, anything that is not PHP code goes here.
src/
Your PHP code lives here.

99% of the time, you'll be working in src/ (PHP files) or app/ (everything else). As you keep reading, you'll learn what can be done inside each of these.

So what about the other directories in the project?

bin/
The famous bin/console file lives here (and other, less important executable files).
tests/
The automated tests (e.g. Unit tests) for your application live here.
var/
This is where automatically-created files are stored, like cache files (var/cache/) and logs (var/logs/).
vendor/
Third-party (i.e. "vendor") libraries live here! These are downloaded via the Composer package manager.
web/
This is the document root for your project: put any publicly accessible files here (e.g. CSS, JS and images).

Bundles & Configuration

Your Symfony application comes pre-installed with a collection of bundles, like FrameworkBundle and TwigBundle. Bundles are similar to the idea of a plugin, but with one important difference: all functionality in a Symfony application comes from a bundle.

Bundles are registered in your app/AppKernel.php file (a rare PHP file in the app/ directory) and each gives you more tools, sometimes called services:

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class AppKernel extends Kernel
{
    public function registerBundles()
    {
        $bundles = array(
            new Symfony\Bundle\FrameworkBundle\FrameworkBundle(),
            new Symfony\Bundle\TwigBundle\TwigBundle(),
            // ...
        );
        // ...

        return $bundles;
    }

    // ...
}

For example, TwigBundle is responsible for adding the Twig tool to your app!

Eventually, you'll download and add more third-party bundles to your app in order to get even more tools. Imagine a bundle that helps you create paginated lists. That exists!

You can control how your bundles behave via the app/config/config.yml file. That file - and other details like environments & parameters - are discussed in the Configuring Symfony (and Environments) chapter.

What's Next?

Congrats! You're already starting to master Symfony and learn a whole new way of building beautiful, functional, fast and maintainable apps.

Ok, time to finish mastering the fundamentals by reading these chapters:

Then, learn about other important topics like the service container, the form system, using Doctrine (if you need to query a database) and more!

Have fun!

Go Deeper with HTTP & Framework Fundamentals

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.