What is Symfony routing component?

The Symfony routing component is a very popular routing component that is adapted from several frameworks and provides a lot of flexibility if you want to set up routing in your PHP application.

If you have built a custom PHP application and are looking for a feature-rich routing library, then Symfony Routing Component is one of the best candidates. It also allows you to define your application's routes in YAML format.

Starting with installation and configuration, we will demonstrate the various options of this component for routing configuration through practical examples. In this article you will learn:

• Symfony routing component installation and configuration
• How to set up a basic route
• How to load routes from YAML file
• Create routes as comments: Recommended way

Installation and Configuration

In this section, we will install the libraries required to set up routing in a PHP application. I assume you already have Composer installed on your system as we need it to install the necessary libraries available on Packagist.

After installing Composer, please continue using the following commands to install the core routing components.

$composer require symfony/routing

While the routing component itself is sufficient to provide comprehensive routing capabilities in your application, we will also go ahead and install a few additional components to make our lives easier and enrich the existing core routing functionality.

First, we will proceed to install the HttpFoundation component, which provides object-oriented wrappers for PHP global variables and response-related functions. It ensures that you don't need to directly access global variables like $_GET, $_POST, etc.

$composer require symfony/http-foundation

Next, if you want to define application routes in a YAML file instead of PHP code, the YAML component comes into play as it helps you convert YAML strings to PHP arrays and vice versa.

$composer require symfony/yaml

Finally, we will install the Config component, which provides several utility classes to initialize and process configuration values ??defined in different types of files (such as YAML, INI, XML, etc.). In our case we will use this to load routes from a YAML file.

$composer require symfony/config

That’s the installation part, but how are you supposed to use it? In fact, just include the autoload.php file created by Composer in your application, as shown in the following code snippet.

<?php
require_once './vendor/autoload.php';
 
// application code
?>

Set up basic routing

In the previous section, we completed the installation of the necessary routing components. Now you can instantly set up routing in your PHP application.

Let's go ahead and create the basic_routes.php file with the following content.

<?php
require_once './vendor/autoload.php';
 
use Symfony\Component\Routing\Matcher\UrlMatcher;
use Symfony\Component\Routing\RequestContext;
use Symfony\Component\Routing\RouteCollection;
use Symfony\Component\Routing\Route;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Routing\Generator\UrlGenerator;
use Symfony\Component\Routing\Exception\ResourceNotFoundException;
 
try
{
    // Init basic route
    $foo_route = new Route(
      '/foo',
      array('controller' => 'FooController')
    );
 
    // Init route with dynamic placeholders
    $foo_placeholder_route = new Route(
      '/foo/{id}',
      array('controller' => 'FooController', 'method'=>'load'),
      array('id' => '[0-9]+')
    );
 
    // Add Route object(s) to RouteCollection object
    $routes = new RouteCollection();
    $routes->add('foo_route', $foo_route);
    $routes->add('foo_placeholder_route', $foo_placeholder_route);
 
    // Init RequestContext object
    $context = new RequestContext();
    $context->fromRequest(Request::createFromGlobals());
 
    // Init UrlMatcher object
    $matcher = new UrlMatcher($routes, $context);
 
    // Find the current route
    $parameters = $matcher->match($context->getPathInfo());
 
    // How to generate a SEO URL
    $generator = new UrlGenerator($routes, $context);
    $url = $generator->generate('foo_placeholder_route', array(
      'id' => 123,
    ));
 
    echo '<pre class="brush:php;toolbar:false">';
    print_r($parameters);
 
    echo 'Generated URL: ' . $url;
    exit;
}
catch (ResourceNotFoundException $e)
{
  echo $e->getMessage();
}

Setting up routing using the Symfony Routing component usually involves a series of steps listed below.

• Initialize the Route object for each application route.
• Add all Route objects to the RouteCollection object.
• Initialize RequestContext object, which saves the current request context information.
• Initialize the UrlMatcher object by passing the RouteCollection object and the RequestContext object.

Initialize routing objects for different routes

Let's go ahead and define a very basic foo route.

$foo_route = new Route(
  '/foo',
  array('controller' => 'FooController')
);

Route The first parameter to the constructor is the URI path and the second parameter is an array of custom properties to be returned when matching this specific route. Typically, it's a combination of controllers and methods that you call when this route is requested.

Next let’s take a look at parameterized routing.

$foo_placeholder_route = new Route(
  '/foo/{id}',
  array('controller' => 'FooController', 'method'=>'load'),
  array('id' => '[0-9]+')
);

The above route can match foo/1, foo/123 and other similar URIs. Note that we restricted the {id} parameter to only numeric values, so it will not match a URI like foo/bar because {id} Parameters are provided as strings.

Add all routing objects to the RouteCollection object

The next step is to add the route object we initialized in the previous section to the RouteCollection object.

$routes = new RouteCollection();
$routes->add('foo_route', $foo_route);
$routes->add('foo_placeholder_route', $foo_placeholder_route);

正如您所看到的，這非常簡單，您只需要使用 RouteCollection 對象的 add 方法來添加路由對象。 add 方法的第一個參數(shù)是路由名稱，第二個參數(shù)是路由對象本身。

初始化 RequestContext 對象

接下來，我們需要初始化RequestContext對象，該對象保存當前請求上下文信息。當我們初始化 UrlMatcher 對象時，我們將需要這個對象，因為我們稍后會詳細介紹它。

$context = new RequestContext();
$context->fromRequest(Request::createFromGlobals());

初始化 UrlMatcher 對象

最后，我們需要初始化 UrlMatcher 對象以及路由和上下文信息。

// Init UrlMatcher object
$matcher = new UrlMatcher($routes, $context);

現(xiàn)在，我們擁有了可以匹配路線的一切。

如何匹配路由

這是 UrlMatcher 對象的 match 方法，它允許您將任何路由與一組預(yù)定義路由進行匹配。

match 方法將 URI 作為其第一個參數(shù)，并嘗試將其與預(yù)定義的路由進行匹配。如果找到該路由，它將返回與該路由關(guān)聯(lián)的自定義屬性。另一方面，如果沒有與當前 URI 關(guān)聯(lián)的路由，它會拋出 ResourceNotFoundException 異常。

$parameters = $matcher->match($context->getPathInfo());

在我們的例子中，我們通過從 $context 對象獲取當前 URI 來提供它。因此，如果您訪問 https://your-domain/basic_routes.php/foo URL，則 $context->getPathInfo() 返回 foo，并且我們已經(jīng)為 foo URI 定義了一條路由，因此它應(yīng)該返回以下內(nèi)容。

Array
(
    [controller] => FooController
    [_route] => foo_route
)

現(xiàn)在，讓我們繼續(xù)訪問 http://your-domain/basic_routes.php/foo/123 URL 來測試參數(shù)化路由。

Array
(
    [controller] => FooController
    [method] => load
    [id] => 123
    [_route] => foo_placeholder_route
)

如果您可以看到 id 參數(shù)與適當?shù)闹?123 綁定，則說明有效。

接下來，讓我們嘗試訪問不存在的路由，例如 http://your-domain/basic_routes.php/unknown-route，您應(yīng)該會看到以下消息。

No routes found for "/unknown-route".

這就是如何使用 match 方法查找路由。

除此之外，您還可以使用路由組件在應(yīng)用程序中生成鏈接。提供了 RouteCollection 和 RequestContext 對象，UrlGenerator 允許您為特定路由構(gòu)建鏈接。

$generator = new UrlGenerator($routes, $context);
$url = $generator->generate('foo_placeholder_route', array(
  'id' => 123,
));

generate 方法的第一個參數(shù)是路由名稱，第二個參數(shù)是數(shù)組，如果是參數(shù)化路由，則可以包含參數(shù)。上面的代碼應(yīng)該生成 /basic_routes.php/foo/123 URL。

從 YAML 文件加載路由

在上一節(jié)中，我們使用 Route 和 RouteCollection 對象構(gòu)建了自定義路由。事實上，路由組件提供了不同的方式供您選擇來實例化路由。您可以從各種加載器中進行選擇，例如 YamlFileLoader、XmlFileLoader 和 PhpFileLoader。

在本節(jié)中，我們將通過 YamlFileLoader 加載器來了解如何從 YAML 文件加載路由。

路由 YAML 文件

繼續(xù)創(chuàng)建包含以下內(nèi)容的 routes.yaml 文件。

foo_route:
    path:     /foo
    controller: App\Controller\FooController::index
    methods:    GET
 
foo_placeholder_route:
    path:     /foo/{id}
    controller: App\Controller\FooController::load
    methods:    GET
    requirements:
        id: '[0-9]+'

示例文件

接下來，繼續(xù)使用以下內(nèi)容創(chuàng)建 load_routes_from_yaml.php 文件。

load('routes.yaml');
 
    // Init RequestContext object
    $context = new RequestContext();
    $context->fromRequest(Request::createFromGlobals());
 
    // Init UrlMatcher object
    $matcher = new UrlMatcher($routes, $context);
 
    // Find the current route
    $parameters = $matcher->match($context->getPathInfo());
 
    // How to generate a SEO URL
    $generator = new UrlGenerator($routes, $context);
    $url = $generator->generate('foo_placeholder_route', array(
      'id' => 123,
    ));
 
    echo '
';
    print_r($parameters);
 
    echo 'Generated URL: ' . $url;
    exit;
}
catch (ResourceNotFoundException $e)
{
  echo $e->getMessage();
}

在這種情況下唯一不同的是我們初始化路由的方式！
$fileLocator = new FileLocator(array(__DIR__));
$loader = new YamlFileLoader($fileLocator);
$routes = $loader->load('routes.yaml');

我們使用 YamlFileLoader 加載器從 routes.yaml 文件加載路由，而不是直接在 PHP 本身中對其進行初始化。除此之外，一切都是相同的，并且應(yīng)該產(chǎn)生與 basic_routes.php 文件相同的結(jié)果。
一體化路由器
在本節(jié)中，我們將介紹 Router 類，它允許您使用更少的代碼行快速設(shè)置路由。
繼續(xù)制作包含以下內(nèi)容的 all_in_one_router.php 文件。
<?php
require_once './vendor/autoload.php';
 
use Symfony\Component\Routing\RequestContext;
use Symfony\Component\Routing\Router;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Routing\Generator\UrlGenerator;
use Symfony\Component\Config\FileLocator;
use Symfony\Component\Routing\Loader\YamlFileLoader;
use Symfony\Component\Routing\Exception\ResourceNotFoundException;
 
try
{
    $fileLocator = new FileLocator(array(__DIR__));
 
    $requestContext = new RequestContext();
    $requestContext->fromRequest(Request::createFromGlobals());
 
    $router = new Router(
        new YamlFileLoader($fileLocator),
        'routes.yaml',
        array('cache_dir' => __DIR__.'/cache'),
        $requestContext
    );
 
    // Find the current route
    $parameters = $router->match($requestContext->getPathInfo());
 
    // How to generate a SEO URL
    $routes = $router->getRouteCollection();
    $generator = new UrlGenerator($routes, $requestContext);
    $url = $generator->generate('foo_placeholder_route', array(
      'id' => 123,
    ));
 
    echo '<pre class="brush:php;toolbar:false">';
    print_r($parameters);
 
    echo 'Generated URL: ' . $url;
    exit;
}
catch (ResourceNotFoundException $e)
{
  echo $e->getMessage();
}

一切都幾乎相同，除了我們實例化了 Router 對象以及必要的依賴項。
$router = new Router(
    new YamlFileLoader($fileLocator),
    'routes.yaml',
    array('cache_dir' => __DIR__.'/cache'),
    $requestContext
);

完成后，您可以立即使用 Router 對象的 match 方法進行路由映射。
$parameters = $router->match($requestContext->getPathInfo());

此外，您還需要使用 Router 對象的 getRouteCollection 方法來獲取路由。
$routes = $router->getRouteCollection();

將路由創(chuàng)建為注釋：推薦方式
在本節(jié)中，我們將討論如何實現(xiàn)基于注釋的路由。它正在成為在不同框架之間定義路由的最流行的方法之一。
在我們繼續(xù)實現(xiàn)基于注釋的路由之前，我們需要安裝幾個軟件包。讓我們快速完成此操作，如以下代碼片段所示。
$composer require symfony/framework-bundle
$composer require doctrine/annotations
$composer require doctrine/cache

如您所見，我們安裝了三個不同的組件。
在您的 composer.json 文件中，添加以下內(nèi)容：
"autoload": {
    "psr-4": {
        "App\\": "app/"
    }
}

現(xiàn)在，運行以下命令。
$composer dump-autoload

現(xiàn)在，我們準備好文件了。
繼續(xù)創(chuàng)建包含以下內(nèi)容的 index.php 文件。
load(__DIR__ . '/src/Controller/');
$context = new RequestContext();
$context->fromRequest(Request::createFromGlobals());

$matcher = new UrlMatcher($routes, $context);
$parameters = $matcher->match($context->getPathInfo());

$controllerInfo = explode('::',$parameters['_controller']);

$controller = new $controllerInfo[0];
$action = $controllerInfo[1];

$controller->$action();

現(xiàn)在，讓我們在 src/Controller/FooController.php 中創(chuàng)建包含以下內(nèi)容的控制器文件。
<?php
namespace App\Controller;

use Symfony\Component\Routing\Annotation\Route;

class DefaultController
{
    /**
     * @Route("/",name="index")
     */
    public function index()
    {
        echo "Index action";
    }

    /**
     * @Route("/hello",name="hello")
     */
    public function hello()
    {
        echo "Hello action";
    }
}

您可能已經(jīng)注意到，我們以注釋的形式為每個方法定義了路由。這種方法的好處是，它允許您在與這些路由關(guān)聯(lián)的控制器的代碼旁邊定義路由。
繼續(xù)訪問 https://your-domain/index.php/ URL。根據(jù)以下路由配置，它應(yīng)該調(diào)用 index 方法。
/**
 * @Route("/",name="index")
 */

另一方面，如果您嘗試訪問 http://your-domain/index.php/hello URL，它應(yīng)該調(diào)用 DefaultController 控制器的 hello 方法類。
這就是基于注釋的路由的工作原理！
結(jié)論
繼續(xù)探索路由組件中可用的其他選項。
今天，我們探索了 Symfony 路由組件，它使得在 PHP 應(yīng)用程序中實現(xiàn)路由變得輕而易舉。在此過程中，我們創(chuàng)建了一些示例來演示路由組件的各個方面。 
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