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Routing

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Routing

Beautiful URLs are an absolute 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 should you need to hunt down and update to make the change? If you're using Symfony's router, the change is simple.

The Symfony router lets you define creative URLs that you map to different areas of your application. By the end of this chapter, you'll be able to:

  • Create complex routes that map to controllers
  • Generate URLs inside templates and controllers
  • Load routing resources from bundles (or anywhere else)
  • Debug your routes

Routing in Action

A route is a map from a URL path to a controller. For example, suppose you want to match any URL like /blog/my-post or /blog/all-about-symfony and send it to a controller that can look up and render that blog entry. The route is simple:

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

use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;

class BlogController extends Controller
{
    /**
     * @Route("/blog/{slug}", name="blog_show")
     */
    public function showAction($slug)
    {
        // ...
    }
}

2.2

The path option was introduced in Symfony 2.2, pattern is used in older versions.

The path defined by the blog_show route acts like /blog/* where the wildcard is given the name slug. For the URL /blog/my-blog-post, the slug variable gets a value of my-blog-post, which is available for you to use in your controller (keep reading). The blog_show is the internal name of the route, which doesn't have any meaning yet and just needs to be unique. Later, you'll use it to generate URLs.

If you don't want to use annotations, because you don't like them or because you don't want to depend on the SensioFrameworkExtraBundle, you can also use Yaml, XML or PHP. In these formats, the _controller parameter is a special key that tells Symfony which controller should be executed when a URL matches this route. The _controller string is called the logical name. It follows a pattern that points to a specific PHP class and method, in this case the AppBundle\Controller\BlogController::showAction method.

Congratulations! You've just created your first route and connected it to a controller. Now, when you visit /blog/my-post, the showAction controller will be executed and the $slug variable will be equal to my-post.

This is the goal of the Symfony router: to map the URL of a request to a controller. Along the way, you'll learn all sorts of tricks that make mapping even the most complex URLs easy.

Routing: Under the Hood

When a request is made to your application, it contains an address to the exact "resource" that the client is requesting. This address is called the URL, (or URI), and could be /contact, /blog/read-me, or anything else. Take the following HTTP request for example:

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GET /blog/my-blog-post

The goal of the Symfony routing system is to parse this URL and determine which controller should be executed. The whole process looks like this:

  1. The request is handled by the Symfony front controller (e.g. app.php);
  2. The Symfony core (i.e. Kernel) asks the router to inspect the request;
  3. The router matches the incoming URL to a specific route and returns information about the route, including the controller that should be executed;
  4. The Symfony Kernel executes the controller, which ultimately returns a Response object.
Symfony request flow

The routing layer is a tool that translates the incoming URL into a specific controller to execute.

Creating Routes

Symfony loads all the routes for your application from a single routing configuration file. The file is usually app/config/routing.yml, but can be configured to be anything (including an XML or PHP file) via the application configuration file:

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# app/config/config.yml
framework:
    # ...
    router: { resource: '%kernel.root_dir%/config/routing.yml' }

Tip

Even though all routes are loaded from a single file, it's common practice to include additional routing resources. To do so, just point out in the main routing configuration file which external files should be included. See the Routing section for more information.

Basic Route Configuration

Defining a route is easy, and a typical application will have lots of routes. A basic route consists of just two parts: the path to match and a defaults array:

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// src/AppBundle/Controller/MainController.php

// ...
class MainController extends Controller
{
    /**
     * @Route("/")
     */
    public function homepageAction()
    {
        // ...
    }
}

This route matches the homepage (/) and maps it to the AppBundle:Main:homepage controller. The _controller string is translated by Symfony into an actual PHP function and executed. That process will be explained shortly in the Routing section.

Routing with Placeholders

Of course the routing system supports much more interesting routes. Many routes will contain one or more named "wildcard" placeholders:

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// src/AppBundle/Controller/BlogController.php

// ...
class BlogController extends Controller
{
    /**
     * @Route("/blog/{slug}")
     */
    public function showAction($slug)
    {
        // ...
    }
}

The path will match anything that looks like /blog/*. Even better, the value matching the {slug} placeholder will be available inside your controller. In other words, if the URL is /blog/hello-world, a $slug variable, with a value of hello-world, will be available in the controller. This can be used, for example, to load the blog post matching that string.

The path will not, however, match simply /blog. That's because, by default, all placeholders are required. This can be changed by adding a placeholder value to the defaults array.

Required and Optional Placeholders

To make things more exciting, add a new route that displays a list of all the available blog posts for this imaginary blog application:

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// src/AppBundle/Controller/BlogController.php

// ...
class BlogController extends Controller
{
    // ...

    /**
     * @Route("/blog")
     */
    public function indexAction()
    {
        // ...
    }
}

So far, this route is as simple as possible - it contains no placeholders and will only match the exact URL /blog. But what if you need this route to support pagination, where /blog/2 displays the second page of blog entries? Update the route to have a new {page} placeholder:

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// src/AppBundle/Controller/BlogController.php

// ...

/**
 * @Route("/blog/{page}")
 */
public function indexAction($page)
{
    // ...
}

Like the {slug} placeholder before, the value matching {page} will be available inside your controller. Its value can be used to determine which set of blog posts to display for the given page.

But hold on! Since placeholders are required by default, this route will no longer match on simply /blog. Instead, to see page 1 of the blog, you'd need to use the URL /blog/1! Since that's no way for a rich web app to behave, modify the route to make the {page} parameter optional. This is done by including it in the defaults collection:

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// src/AppBundle/Controller/BlogController.php

// ...

/**
 * @Route("/blog/{page}", defaults={"page" = 1})
 */
public function indexAction($page)
{
    // ...
}

By adding page to the defaults key, the {page} placeholder is no longer required. The URL /blog will match this route and the value of the page parameter will be set to 1. The URL /blog/2 will also match, giving the page parameter a value of 2. Perfect.

URL Route Parameters
/blog blog {page} = 1
/blog/1 blog {page} = 1
/blog/2 blog {page} = 2

Caution

Of course, you can have more than one optional placeholder (e.g. /blog/{slug}/{page}), but everything after an optional placeholder must be optional. For example, /{page}/blog is a valid path, but page will always be required (i.e. simply /blog will not match this route).

Tip

Routes with optional parameters at the end will not match on requests with a trailing slash (i.e. /blog/ will not match, /blog will match).

Adding Requirements

Take a quick look at the routes that have been created so far:

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// src/AppBundle/Controller/BlogController.php

// ...
class BlogController extends Controller
{
    /**
     * @Route("/blog/{page}", defaults={"page" = 1})
     */
    public function indexAction($page)
    {
        // ...
    }

    /**
     * @Route("/blog/{slug}")
     */
    public function showAction($slug)
    {
        // ...
    }
}

Can you spot the problem? Notice that both routes have patterns that match URLs that look like /blog/*. The Symfony router will always choose the first matching route it finds. In other words, the blog_show route will never be matched. Instead, a URL like /blog/my-blog-post will match the first route (blog) and return a nonsense value of my-blog-post to the {page} parameter.

URL Route Parameters
/blog/2 blog {page} = 2
/blog/my-blog-post blog {page} = "my-blog-post"

The answer to the problem is to add route requirements. The routes in this example would work perfectly if the /blog/{page} path only matched URLs where the {page} portion is an integer. Fortunately, regular expression requirements can easily be added for each parameter. For example:

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// src/AppBundle/Controller/BlogController.php

// ...

/**
 * @Route("/blog/{page}", defaults={"page": 1}, requirements={
 *     "page": "\d+"
 * })
 */
public function indexAction($page)
{
    // ...
}

The \d+ requirement is a regular expression that says that the value of the {page} parameter must be a digit (i.e. a number). The blog route will still match on a URL like /blog/2 (because 2 is a number), but it will no longer match a URL like /blog/my-blog-post (because my-blog-post is not a number).

As a result, a URL like /blog/my-blog-post will now properly match the blog_show route.

URL Route Parameters
/blog/2 blog {page} = 2
/blog/my-blog-post blog_show {slug} = my-blog-post
/blog/2-my-blog-post blog_show {slug} = 2-my-blog-post

Earlier Routes always Win

What this all means is that the order of the routes is very important. If the blog_show route were placed above the blog route, the URL /blog/2 would match blog_show instead of blog since the {slug} parameter of blog_show has no requirements. By using proper ordering and clever requirements, you can accomplish just about anything.

Since the parameter requirements are regular expressions, the complexity and flexibility of each requirement is entirely up to you. Suppose the homepage of your application is available in two different languages, based on the URL:

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// src/AppBundle/Controller/MainController.php

// ...
class MainController extends Controller
{
    /**
     * @Route("/{_locale}", defaults={"_locale": "en"}, requirements={
     *     "_locale": "en|fr"
     * })
     */
    public function homepageAction($_locale)
    {
    }
}

For incoming requests, the {_locale} portion of the URL is matched against the regular expression (en|fr).

Path Parameters
/ {_locale} = "en"
/en {_locale} = "en"
/fr {_locale} = "fr"
/es won't match this route

Tip

The route requirements can also include container parameters, as explained in this article. This comes in handy when the regular expression is very complex and used repeatedly in your application.

Adding HTTP Method Requirements

In addition to the URL, you can also match on the method of the incoming request (i.e. GET, HEAD, POST, PUT, DELETE). Suppose you create an API for your blog and you have 2 routes: One for displaying a post (on a GET or HEAD request) and one for updating a post (on a PUT request). This can be accomplished with the following route configuration:

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

use Sensio\Bundle\FrameworkExtraBundle\Configuration\Method;
// ...

class BlogApiController extends Controller
{
    /**
     * @Route("/api/posts/{id}")
     * @Method({"GET","HEAD"})
     */
    public function showAction($id)
    {
        // ... return a JSON response with the post
    }

    /**
     * @Route("/api/posts/{id}")
     * @Method("PUT")
     */
    public function editAction($id)
    {
        // ... edit a post
    }
}

2.2

The methods option was introduced in Symfony 2.2. Use the _method requirement in older versions.

Despite the fact that these two routes have identical paths (/api/posts/{id}), the first route will match only GET or HEAD requests and the second route will match only PUT requests. This means that you can display and edit the post with the same URL, while using distinct controllers for the two actions.

Note

If no methods are specified, the route will match on all methods.

Adding a Host Requirement

2.2

Host matching support was introduced in Symfony 2.2

You can also match on the HTTP host of the incoming request. For more information, see How to Match a Route Based on the Host in the Routing component documentation.

Advanced Routing Example

At this point, you have everything you need to create a powerful routing structure in Symfony. The following is an example of just how flexible the routing system can be:

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// src/AppBundle/Controller/ArticleController.php

// ...
class ArticleController extends Controller
{
    /**
     * @Route(
     *     "/articles/{_locale}/{year}/{title}.{_format}",
     *     defaults={"_format": "html"},
     *     requirements={
     *         "_locale": "en|fr",
     *         "_format": "html|rss",
     *         "year": "\d+"
     *     }
     * )
     */
    public function showAction($_locale, $year, $title)
    {
    }
}

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

The Special _format Routing Parameter

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). It can also be used in the controller to render a different template for each value of _format. The _format parameter is a very powerful way to render the same content in different formats.

In Symfony versions previous to 3.0, it is possible to override the request format by adding a query parameter named _format (for example: /foo/bar?_format=json). Relying on this behavior not only is considered a bad practice but it will complicate the upgrade of your applications to Symfony 3.

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".

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 three 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).
_locale
Used to set the locale on the request (read more).
.. index::
single: Routing; Controllers single: Controller; String naming format

Controller Naming Pattern

Every route must have a _controller parameter, which dictates which controller should be executed when that route is matched. This parameter uses a simple string pattern called the logical controller name, which Symfony maps to a specific PHP method and class. The pattern has three parts, each separated by a colon:

bundle:controller:action

For example, a _controller value of AppBundle:Blog:show means:

Bundle Controller Class Method Name
AppBundle BlogController showAction

The controller might look like this:

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

use Symfony\Bundle\FrameworkBundle\Controller\Controller;

class BlogController extends Controller
{
    public function showAction($slug)
    {
        // ...
    }
}

Notice that Symfony adds the string Controller to the class name (Blog => BlogController) and Action to the method name (show => showAction).

You could also refer to this controller using its fully-qualified class name and method: AppBundle\Controller\BlogController::showAction. But if you follow some simple conventions, the logical name is more concise and allows more flexibility.

Note

In addition to using the logical name or the fully-qualified class name, Symfony supports a third way of referring to a controller. This method uses just one colon separator (e.g. service_name:indexAction) and refers to the controller as a service (see How to Define Controllers as Services).

Route Parameters and Controller Arguments

The route parameters (e.g. {slug}) are especially important because each is made available as an argument to the controller method:

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

In reality, the entire defaults collection is merged with the parameter values to form a single array. Each key of that array is available as an argument on the controller.

In other words, for each argument of your controller method, Symfony looks for a route parameter of that name and assigns its value to that argument. In the advanced example above, any combination (in any order) of the following variables could be used as arguments to the showAction() method:

  • $_locale
  • $year
  • $title
  • $_format
  • $_controller
  • $_route

Since the placeholders and defaults collection are merged together, even the $_controller variable is available. For a more detailed discussion, see Controller.

Tip

The special $_route variable is set to the name of the route that was matched.

You can even add extra information to your route definition and access it within your controller. For more information on this topic, see How to Pass Extra Information from a Route to a Controller.

Including External Routing Resources

All routes are loaded via a single configuration file - usually app/config/routing.yml (see Creating Routes above). However, if you use routing annotations, you'll need to point the router to the controllers with the annotations. This can be done by "importing" directories into the routing configuration:

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# app/config/routing.yml
app:
    resource: '@AppBundle/Controller/'
    type:     annotation # required to enable the Annotation reader for this resource

Note

When importing resources from YAML, the key (e.g. app) is meaningless. Just be sure that it's unique so no other lines override it.

The resource key loads the given routing resource. In this example the resource is a directory, where the @AppBundle shortcut syntax resolves to the full path of the AppBundle. When pointing to a directory, all files in that directory are parsed and put into the routing.

Note

You can also include other routing configuration files, this is often used to import the routing of third party bundles:

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# app/config/routing.yml
app:
    resource: '@AcmeOtherBundle/Resources/config/routing.yml'

Prefixing Imported Routes

You can also choose to provide a "prefix" for the imported routes. For example, suppose you want to prefix all routes in the AppBundle with /site (e.g. /site/blog/{slug} instead of /blog/{slug}):

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# app/config/routing.yml
app:
    resource: '@AppBundle/Controller/'
    type:     annotation
    prefix:   /site

The path of each route being loaded from the new routing resource will now be prefixed with the string /site.

Adding a Host Requirement to Imported Routes

2.2

Host matching support was introduced in Symfony 2.2

You can set the host regex on imported routes. For more information, see How to Match a Route Based on the Host.

Visualizing & Debugging Routes

While adding and customizing routes, it's helpful to be able to visualize and get detailed information about your routes. A great way to see every route in your application is via the router:debug console command. Execute the command by running the following from the root of your project.

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$ php app/console router:debug

This command will print a helpful list of all the configured routes in your application:

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homepage              ANY       /
contact               GET       /contact
contact_process       POST      /contact
article_show          ANY       /articles/{_locale}/{year}/{title}.{_format}
blog                  ANY       /blog/{page}
blog_show             ANY       /blog/{slug}

You can also get very specific information on a single route by including the route name after the command:

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$ php app/console router:debug article_show

Likewise, if you want to test whether a URL matches a given route, you can use the router:match console command:

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$ php app/console router:match /blog/my-latest-post

This command will print which route the URL matches.

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Route "blog_show" matches

Generating URLs

The routing system should also be used to generate URLs. In reality, routing is a bidirectional system: mapping the URL to a controller+parameters and a route+parameters back to a URL. The match() and generate() methods form this bidirectional system. Take the blog_show example route from earlier:

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$params = $this->get('router')->match('/blog/my-blog-post');
// array(
//     'slug'        => 'my-blog-post',
//     '_controller' => 'AppBundle:Blog:show',
// )

$uri = $this->get('router')->generate('blog_show', array(
    'slug' => 'my-blog-post'
));
// /blog/my-blog-post

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 showAction($slug)
    {
        // ...

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

Note

The generateUrl() method defined in the base Controller class is just a shortcut for this code:

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$url = $this->container->get('router')->generate(
    'blog_show',
    array('slug' => 'my-blog-post')
);

In an upcoming section, you'll learn how to generate URLs from inside templates.

Tip

If the front-end of your application uses Ajax requests, you might want to be able to generate URLs in JavaScript based on your routing configuration. By using the FOSJsRoutingBundle, you can do exactly that:

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var url = Routing.generate(
    'blog_show',
    {"slug": 'my-blog-post'}
);

For more information, see the documentation for that bundle.

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

The most common place to generate a URL is from within a template when linking between pages in your application. This is done just as before, but using a template helper function:

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<a href="{{ path('blog_show', {'slug': 'my-blog-post'}) }}">
  Read this blog post.
</a>

Generating Absolute URLs

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

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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

From a template, in Twig, simply use the url() function (which generates an absolute URL) rather than the path() function (which generates a relative URL). In PHP, pass true to generate():

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<a href="{{ url('blog_show', {'slug': 'my-blog-post'}) }}">
  Read this blog post.
</a>

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.

Summary

Routing is a system for mapping the URL of incoming requests to the controller function that should be called to process the request. It both allows you to specify beautiful URLs and keeps the functionality of your application decoupled from those URLs. Routing is a bidirectional mechanism, meaning that it should also be used to generate URLs.

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