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 Symfony2 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:

New in version 2.2: The path option is new in Symfony2.2, 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 _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:

// src/Acme/BlogBundle/Controller/BlogController.php
namespace Acme\BlogBundle\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;

class BlogController extends Controller
{
    public function showAction($slug)
    {
        // use the $slug variable to query the database
        $blog = ...;

        return $this->render('AcmeBlogBundle:Blog:show.html.twig', array(
            'blog' => $blog,
        ));
    }
}

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 Symfony2 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:

GET /blog/my-blog-post

The goal of the Symfony2 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 Symfony2 front controller (e.g. app.php);
2. The Symfony2 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 Symfony2 Kernel executes the controller, which ultimately returns a Response object.

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:

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 Including External Routing Resources 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:

This route matches the homepage (/) and maps it to the AcmeDemoBundle:Main:homepage controller. The _controller string is translated by Symfony2 into an actual PHP function and executed. That process will be explained shortly in the Controller Naming Pattern section.

Routing with Placeholders

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

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:

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:

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:

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.

/blog	{page} = 1
/blog/1	{page} = 1
/blog/2	{page} = 2

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:

Can you spot the problem? Notice that both routes have patterns that match URL’s 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:

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

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:

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

/	{culture} = en
/en	{culture} = en
/fr	{culture} = fr
/es	won’t match this route

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 have a contact form with two controllers - one for displaying the form (on a GET request) and one for processing the form when it’s submitted (on a POST request). This can be accomplished with the following route configuration:

New in version 2.2: The methods option is added in Symfony2.2. Use the _method requirement in older versions.

Despite the fact that these two routes have identical paths (/contact), the first route will match only GET requests and the second route will match only POST requests. This means that you can display the form and submit the form via 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

New in version 2.2: Host matching support was added in Symfony 2.2

You can also match on the HTTP host of the incoming request. For more information, see /components/routing/hostname_pattern 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:

As you’ve seen, this route will only match if the {culture} 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 such 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.

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 “/cookbook/routing/service_container_parameters.

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);

Tip

If you use the _locale parameter in a route, that value will also be stored on the session so that subsequent requests keep this same locale.

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 AcmeBlogBundle:Blog:show means:

Bundle	Controller Class	Method Name
AcmeBlogBundle	BlogController	showAction

The controller might look like this:

// src/Acme/BlogBundle/Controller/BlogController.php
namespace Acme\BlogBundle\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: Acme\BlogBundle\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 /cookbook/controller/service).

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:

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:

• $culture
• $year
• $title
• $_format
• $_controller

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

Tip

You can also use a special $_route variable, which is set to the name of the route that was matched.

Including External Routing Resources

All routes are loaded via a single configuration file - usually app/config/routing.yml (see Creating Routes above). Commonly, however, you’ll want to load routes from other places, like a routing file that lives inside a bundle. This can be done by “importing” that file:

Note

When importing resources from YAML, the key (e.g. acme_hello) 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 the full path to a file, where the @AcmeHelloBundle shortcut syntax resolves to the path of that bundle. The imported file might look like this:

The routes from this file are parsed and loaded in the same way as the main routing file.

Prefixing Imported Routes

You can also choose to provide a “prefix” for the imported routes. For example, suppose you want the acme_hello route to have a final path of /admin/hello/{name} instead of simply /hello/{name}:

The string /admin will now be prepended to the path of each route loaded from the new routing resource.

Tip

You can also define routes using annotations. See the FrameworkExtraBundle documentation to see how.

Adding a Host regex to Imported Routes

New in version 2.2: Host matching support was added in Symfony 2.2

You can set the host regex on imported routes. For more information, see component-routing-host-imported.

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.

$ php app/console router:debug

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

homepage              ANY       /
contact               GET       /contact
contact_process       POST      /contact
article_show          ANY       /articles/{culture}/{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:

$ 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:

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

This command will print which route the URL matches.

Route "blog_show" matches

Generating URLs

The routing system should also be used to generate URLs. In reality, routing is a bi-directional system: mapping the URL to a controller+parameters and a route+parameters back to a URL. The :method:`Symfony\\Component\\Routing\\Router::match` and :method:`Symfony\\Component\\Routing\\Router::generate` methods form this bi-directional system. Take the blog_show example route from earlier:

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

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

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

Note

In controllers that extend Symfony’s base Symfony\Bundle\FrameworkBundle\Controller\Controller, you can use the :method:`Symfony\\Bundle\\FrameworkBundle\\Controller\\Controller::generateUrl` method, which call’s the router service’s :method:`Symfony\\Component\\Routing\\Router::generate` method.

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

Tip

If the frontend 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:

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

For more information, see the documentation for that bundle.

Generating Absolute URLs

By default, the router will generate relative URLs (e.g. /blog). To generate an absolute URL, simply pass true to the third argument of the generate() method:

$this->get('router')->generate('blog_show', array('slug' => 'my-blog-post'), true);
// http://www.example.com/blog/my-blog-post

Note

The host that’s used when generating an absolute URL is the host of the current Request object. This is detected automatically based on server information supplied by PHP. When generating absolute URLs for scripts run from the command line, you’ll need to manually set the desired host on the RequestContext object:

$this->get('router')->getContext()->setHost('www.example.com');

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:

$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:

Absolute URLs can also be generated.

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 two-way mechanism, meaning that it should also be used to generate URLs.

Learn more from the Cookbook

• /cookbook/routing/scheme