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Routing

Routing

Beautiful URLs are a must for any serious web application. This means leaving behind ugly URLs like index.php?article_id=57 in favor of something like /read/intro-to-symfony.

Having flexibility is even more important. What if you need to change the URL of a page from /blog to /news? How many links would you need to hunt down and update to make the change? If you're using Symfony's router, the change is simple.

Creating Routes

A route is a map from a URL path to a controller. Suppose you want one route that matches /blog exactly and another more dynamic route that can match any URL like /blog/my-post or /blog/all-about-symfony:

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    // src/Controller/BlogController.php
    namespace App\Controller;
    
    use Symfony\Bundle\FrameworkBundle\Controller\Controller;
    use Symfony\Component\Routing\Annotation\Route;
    
    class BlogController extends Controller
    {
        /**
         * Matches /blog exactly
         *
         * @Route("/blog", name="blog_list")
         */
        public function list()
        {
            // ...
        }
    
        /**
         * Matches /blog/*
         *
         * @Route("/blog/{slug}", name="blog_show")
         */
        public function show($slug)
        {
            // $slug will equal the dynamic part of the URL
            // e.g. at /blog/yay-routing, then $slug='yay-routing'
    
            // ...
        }
    }
    
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    # config/routes.yaml
    blog_list:
        path:     /blog
        controller: App\Controller\BlogController::list
    
    blog_show:
        path:     /blog/{slug}
        controller: App\Controller\BlogController::show
    
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    <!-- config/routes.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <routes xmlns="http://symfony.com/schema/routing"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://symfony.com/schema/routing
            http://symfony.com/schema/routing/routing-1.0.xsd">
    
        <route id="blog_list" path="/blog">
            <controller>App\Controller\BlogController::list</controller>
        </route>
    
        <route id="blog_show" path="/blog/{slug}">
            <controller>App\Controller\BlogController::show</controller>
        </route>
    </routes>
    
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    // config/routes.php
    use Symfony\Component\Routing\RouteCollection;
    use Symfony\Component\Routing\Route;
    use App\Controller\BlogController;
    
    $collection = new RouteCollection();
    $collection->add('blog_list', new Route('/blog', array(
        '_controller' => [BlogController::class, 'list']
    )));
    $collection->add('blog_show', new Route('/blog/{slug}', array(
        '_controller' => [BlogController::class, 'show']
    )));
    
    return $collection;
    

Thanks to these two routes:

  • If the user goes to /blog, the first route is matched and list() is executed;
  • If the user goes to /blog/*, the second route is matched and show() is executed. Because the route path is /blog/{slug}, a $slug variable is passed to show() matching that value. For example, if the user goes to /blog/yay-routing, then $slug will equal yay-routing.

Whenever you have a {placeholder} in your route path, that portion becomes a wildcard: it matches any value. Your controller can now also have an argument called $placeholder (the wildcard and argument names must match).

Each route also has an internal name: blog_list and blog_show. These can be anything (as long as each is unique) and don't have any meaning yet. You'll use them later to generate URLs.

The @Route above each method is called an annotation. If you'd rather configure your routes in YAML, XML or PHP, that's no problem! Just create a new routing file (e.g. routes.xml) and Symfony will automatically use it.

Adding {wildcard} Requirements

Imagine the blog_list route will contain a paginated list of blog posts, with URLs like /blog/2 and /blog/3 for pages 2 and 3. If you change the route's path to /blog/{page}, you'll have a problem:

  • blog_list: /blog/{page} will match /blog/*;
  • blog_show: /blog/{slug} will also match /blog/*.

When two routes match the same URL, the first route that's loaded wins. Unfortunately, that means that /blog/yay-routing will match the blog_list. No good!

To fix this, add a requirement that the {page} wildcard can only match numbers (digits):

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    // src/Controller/BlogController.php
    namespace App\Controller;
    
    use Symfony\Bundle\FrameworkBundle\Controller\Controller;
    use Symfony\Component\Routing\Annotation\Route;
    
    class BlogController extends Controller
    {
        /**
         * @Route("/blog/{page}", name="blog_list", requirements={"page"="\d+"})
         */
        public function list($page)
        {
            // ...
        }
    
        /**
         * @Route("/blog/{slug}", name="blog_show")
         */
        public function show($slug)
        {
            // ...
        }
    }
    
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    # config/routes.yaml
    blog_list:
        path:      /blog/{page}
        controller: App\Controller\BlogController::list
        requirements:
            page: '\d+'
    
    blog_show:
        # ...
    
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    <!-- config/routes.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <routes xmlns="http://symfony.com/schema/routing"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://symfony.com/schema/routing
            http://symfony.com/schema/routing/routing-1.0.xsd">
    
        <route id="blog_list" path="/blog/{page}">
            <controller>App\Controller\BlogController::list</controller>
            <requirement key="page">\d+</requirement>
        </route>
    
        <!-- ... -->
    </routes>
    
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    // config/routes.php
    use Symfony\Component\Routing\RouteCollection;
    use Symfony\Component\Routing\Route;
    use App\Controller\BlogController;
    
    $collection = new RouteCollection();
    $collection->add('blog_list', new Route('/blog/{page}', array(
        '_controller' => [BlogController::class, 'list'],
    ), array(
        'page' => '\d+'
    )));
    
    // ...
    
    return $collection;
    

The \d+ is a regular expression that matches a digit of any length. Now:

URL Route Parameters
/blog/2 blog_list $page = 2
/blog/yay-routing blog_show $slug = yay-routing

To learn about other route requirements - like HTTP method, hostname and dynamic expressions - see How to Define Route Requirements.

Giving {placeholders} a Default Value

In the previous example, the blog_list has a path of /blog/{page}. If the user visits /blog/1, it will match. But if they visit /blog, it will not match. As soon as you add a {placeholder} to a route, it must have a value.

So how can you make blog_list once again match when the user visits /blog? By adding a default value:

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    // src/Controller/BlogController.php
    namespace App\Controller;
    
    use Symfony\Bundle\FrameworkBundle\Controller\Controller;
    use Symfony\Component\Routing\Annotation\Route;
    
    class BlogController extends Controller
    {
        /**
         * @Route("/blog/{page}", name="blog_list", requirements={"page"="\d+"})
         */
        public function list($page = 1)
        {
            // ...
        }
    }
    
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    # config/routes.yaml
    blog_list:
        path:      /blog/{page}
        controller: App\Controller\BlogController::list
        defaults:
            page: 1
        requirements:
            page: '\d+'
    
    blog_show:
        # ...
    
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    <!-- config/routes.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <routes xmlns="http://symfony.com/schema/routing"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://symfony.com/schema/routing
            http://symfony.com/schema/routing/routing-1.0.xsd">
    
        <route id="blog_list" path="/blog/{page}">
            <controller>App\Controller\BlogController::list</controller>
            <default key="page">1</default>
    
            <requirement key="page">\d+</requirement>
        </route>
    
        <!-- ... -->
    </routes>
    
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    // config/routes.php
    use Symfony\Component\Routing\RouteCollection;
    use Symfony\Component\Routing\Route;
    use App\Controller\BlogController;
    
    $collection = new RouteCollection();
    $collection->add('blog_list', new Route(
        '/blog/{page}',
        array(
            '_controller' => [BlogController::class, 'list'],
            'page'        => 1,
        ),
        array(
            'page' => '\d+'
        )
    ));
    
    // ...
    
    return $collection;
    

Now, when the user visits /blog, the blog_list route will match and $page will default to a value of 1.

Advanced Routing Example

With all of this in mind, check out this advanced example:

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    // src/Controller/ArticleController.php
    
    // ...
    class ArticleController extends Controller
    {
        /**
         * @Route(
         *     "/articles/{_locale}/{year}/{slug}.{_format}",
         *     defaults={"_format": "html"},
         *     requirements={
         *         "_locale": "en|fr",
         *         "_format": "html|rss",
         *         "year": "\d+"
         *     }
         * )
         */
        public function show($_locale, $year, $slug)
        {
        }
    }
    
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    # config/routes.yaml
    article_show:
      path:     /articles/{_locale}/{year}/{slug}.{_format}
      controller: App\Controller\ArticleController::show
      defaults:
          _format: html
      requirements:
          _locale:  en|fr
          _format:  html|rss
          year:     \d+
    
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    <!-- config/routes.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <routes xmlns="http://symfony.com/schema/routing"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://symfony.com/schema/routing
            http://symfony.com/schema/routing/routing-1.0.xsd">
    
        <route id="article_show"
            path="/articles/{_locale}/{year}/{slug}.{_format}">
    
            <controller>App\Controller\ArticleController::show</controller>
            <default key="_format">html</default>
            <requirement key="_locale">en|fr</requirement>
            <requirement key="_format">html|rss</requirement>
            <requirement key="year">\d+</requirement>
    
        </route>
    </routes>
    
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    // config/routes.php
    use Symfony\Component\Routing\RouteCollection;
    use Symfony\Component\Routing\Route;
    use App\Controller\ArticleController;
    
    $collection = new RouteCollection();
    $collection->add(
        'article_show',
        new Route('/articles/{_locale}/{year}/{slug}.{_format}', array(
            '_controller' => [ArticleController::class, 'show'],
            '_format'     => 'html',
        ), array(
            '_locale' => 'en|fr',
            '_format' => 'html|rss',
            'year'    => '\d+',
        ))
    );
    
    return $collection;
    

As you've seen, this route will only match if the {_locale} portion of the URL is either en or fr and if the {year} is a number. This route also shows how you can use a dot between placeholders instead of a slash. URLs matching this route might look like:

  • /articles/en/2010/my-post
  • /articles/fr/2010/my-post.rss
  • /articles/en/2013/my-latest-post.html

This example also highlights the special _format routing parameter. When using this parameter, the matched value becomes the "request format" of the Request object.

Ultimately, the request format is used for such things as setting the Content-Type of the response (e.g. a json request format translates into a Content-Type of application/json).

Note

Sometimes you want to make certain parts of your routes globally configurable. Symfony provides you with a way to do this by leveraging service container parameters. Read more about this in "How to Use Service Container Parameters in your Routes".

Caution

A route placeholder name cannot start with a digit and cannot be longer than 32 characters.

Special Routing Parameters

As you've seen, each routing parameter or default value is eventually available as an argument in the controller method. Additionally, there are four parameters that are special: each adds a unique piece of functionality inside your application:

_controller
As you've seen, this parameter is used to determine which controller is executed when the route is matched.
_format
Used to set the request format (read more).
_fragment
Used to set the fragment identifier, the optional last part of a URL that starts with a # character and is used to identify a portion of a document.
_locale
Used to set the locale on the request (read more).

Controller Naming Pattern

The controller value in your routes has a very simple format CONTROLLER_CLASS::METHOD. If your controller is registered as a service, you can also use just one colon separator (e.g. service_name:index).

Tip

To refer to an action that is implemented as the __invoke() method of a controller class, you do not have to pass the method name, but can just use the fully qualified class name (e.g. App\Controller\BlogController).

Generating URLs

The routing system can also generate URLs. In reality, routing is a bidirectional system: mapping the URL to a controller and also a route back to a URL.

To generate a URL, you need to specify the name of the route (e.g. blog_show) and any wildcards (e.g. slug = my-blog-post) used in the path for that route. With this information, any URL can easily be generated:

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class MainController extends Controller
{
    public function show($slug)
    {
        // ...

        // /blog/my-blog-post
        $url = $this->generateUrl(
            'blog_show',
            array('slug' => 'my-blog-post')
        );
    }
}

If you need to generate a URL from a service, type-hint the UrlGeneratorInterface service:

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// src/Service/SomeService.php

use Symfony\Component\Routing\Generator\UrlGeneratorInterface;

class SomeService
{
    private $router;

    public function __construct(UrlGeneratorInterface $router)
    {
        $this->router = $router;
    }

    public function someMethod()
    {
        $url = $this->router->generate(
            'blog_show',
            array('slug' => 'my-blog-post')
        );
        // ...
    }
}

Generating URLs with Query Strings

The generate() method takes an array of wildcard values to generate the URI. But if you pass extra ones, they will be added to the URI as a query string:

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$this->get('router')->generate('blog', array(
    'page' => 2,
    'category' => 'Symfony'
));
// /blog/2?category=Symfony

Generating URLs from a Template

To generate URLs inside Twig, see the templating article: Linking to Pages. If you also need to generate URLs in JavaScript, see How to Generate Routing URLs in JavaScript.

Generating Absolute URLs

By default, the router will generate relative URLs (e.g. /blog). From a controller, pass UrlGeneratorInterface::ABSOLUTE_URL to the third argument of the generateUrl() method:

use Symfony\Component\Routing\Generator\UrlGeneratorInterface;

$this->generateUrl('blog_show', array('slug' => 'my-blog-post'), UrlGeneratorInterface::ABSOLUTE_URL);
// http://www.example.com/blog/my-blog-post

Note

The host that's used when generating an absolute URL is automatically detected using the current Request object. When generating absolute URLs from outside the web context (for instance in a console command) this doesn't work. See How to Generate URLs from the Console to learn how to solve this problem.

Troubleshooting

Here are some common errors you might see while working with routing:

Controller "AppControllerBlogController::show()" requires that you provide a value for the "$slug" argument.

This happens when your controller method has an argument (e.g. $slug):

public function show($slug)
{
    // ..
}

But your route path does not have a {slug} wildcard (e.g. it is /blog/show). Add a {slug} to your route path: /blog/show/{slug} or give the argument a default value (i.e. $slug = null).

Some mandatory parameters are missing ("slug") to generate a URL for route "blog_show".

This means that you're trying to generate a URL to the blog_show route but you are not passing a slug value (which is required, because it has a {slug}) wildcard in the route path. To fix this, pass a slug value when generating the route:

$this->generateUrl('blog_show', array('slug' => 'slug-value'));

// or, in Twig
// {{ path('blog_show', {'slug': 'slug-value'}) }}

Translating Routes

Symfony doesn't support defining routes with different contents depending on the user language. In those cases, you can define multiple routes per controller, one for each supported language; or use any of the bundles created by the community to implement this feature, such as JMSI18nRoutingBundle and BeSimpleI18nRoutingBundle.

Keep Going!

Routing, check! Now, uncover the power of controllers.

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