silex/doc/usage.rst

Usage
=====

Installation
------------

If you want to get started fast, use the `Silex Skeleton`_:

.. code-block:: bash

    composer create-project fabpot/silex-skeleton path/to/install "~2.0"

If you want more flexibility, use Composer_ instead:

.. code-block:: bash

    composer require silex/silex:~2.0

Web Server
----------

All examples in the documentation rely on a well-configured web server; read
the :doc:`webserver documentation<web_servers>` to check yours.

Bootstrap
---------

To bootstrap Silex, all you need to do is require the ``vendor/autoload.php``
file and create an instance of ``Silex\Application``. After your controller
definitions, call the ``run`` method on your application::

    // web/index.php
    require_once __DIR__.'/../vendor/autoload.php';

    $app = new Silex\Application();

    // ... definitions

    $app->run();

.. tip::

    When developing a website, you might want to turn on the debug mode to
    ease debugging::

        $app['debug'] = true;

.. tip::

    If your application is hosted behind a reverse proxy at address ``$ip``,
    and you want Silex to trust the ``X-Forwarded-For*`` headers, you will
    need to run your application like this::

        use Symfony\Component\HttpFoundation\Request;

        Request::setTrustedProxies(array($ip));
        $app->run();

Routing
-------

In Silex you define a route and the controller that is called when that
route is matched. A route pattern consists of:

* *Pattern*: The route pattern defines a path that points to a resource. The
  pattern can include variable parts and you are able to set RegExp
  requirements for them.

* *Method*: One of the following HTTP methods: ``GET``, ``POST``, ``PUT``,
  ``DELETE``, ``PATCH``, or ``OPTIONS``. This describes the interaction with
  the resource.

The controller is defined using a closure like this::

    function () {
        // ... do something
    }

The return value of the closure becomes the content of the page.

Example GET Route
~~~~~~~~~~~~~~~~~

Here is an example definition of a ``GET`` route::

    $blogPosts = array(
        1 => array(
            'date'      => '2011-03-29',
            'author'    => 'igorw',
            'title'     => 'Using Silex',
            'body'      => '...',
        ),
    );

    $app->get('/blog', function () use ($blogPosts) {
        $output = '';
        foreach ($blogPosts as $post) {
            $output .= $post['title'];
            $output .= '<br />';
        }

        return $output;
    });

Visiting ``/blog`` will return a list of blog post titles. The ``use``
statement means something different in this context. It tells the closure to
import the ``$blogPosts`` variable from the outer scope. This allows you to use
it from within the closure.

Dynamic Routing
~~~~~~~~~~~~~~~

Now, you can create another controller for viewing individual blog posts::

    $app->get('/blog/{id}', function (Silex\Application $app, $id) use ($blogPosts) {
        if (!isset($blogPosts[$id])) {
            $app->abort(404, "Post $id does not exist.");
        }

        $post = $blogPosts[$id];

        return  "<h1>{$post['title']}</h1>".
                "<p>{$post['body']}</p>";
    });

This route definition has a variable ``{id}`` part which is passed to the
closure.

The current ``Application`` is automatically injected by Silex to the Closure
thanks to the type hinting.

When the post does not exist, you are using ``abort()`` to stop the request
early. It actually throws an exception, which you will see how to handle later
on.

Example POST Route
~~~~~~~~~~~~~~~~~~

POST routes signify the creation of a resource. An example for this is a
feedback form. You will use the ``mail`` function to send an e-mail::

    use Symfony\Component\HttpFoundation\Request;
    use Symfony\Component\HttpFoundation\Response;

    $app->post('/feedback', function (Request $request) {
        $message = $request->get('message');
        mail('feedback@yoursite.com', '[YourSite] Feedback', $message);

        return new Response('Thank you for your feedback!', 201);
    });

It is pretty straightforward.

.. note::

    There is a :doc:`SwiftmailerServiceProvider <providers/swiftmailer>`
    included that you can use instead of ``mail()``.

The current ``request`` is automatically injected by Silex to the Closure
thanks to the type hinting. It is an instance of
Request_, so you can fetch variables using the request ``get`` method.

Instead of returning a string you are returning an instance of Response_.
This allows setting an HTTP status code, in this case it is set to
``201 Created``.

.. note::

    Silex always uses a ``Response`` internally, it converts strings to
    responses with status code ``200``.

Other methods
~~~~~~~~~~~~~

You can create controllers for most HTTP methods. Just call one of these
methods on your application: ``get``, ``post``, ``put``, ``delete``, ``patch``, ``options``::

    $app->put('/blog/{id}', function ($id) {
        // ...
    });

    $app->delete('/blog/{id}', function ($id) {
        // ...
    });

    $app->patch('/blog/{id}', function ($id) {
        // ...
    });

.. tip::

    Forms in most web browsers do not directly support the use of other HTTP
    methods. To use methods other than GET and POST you can utilize a special
    form field with a name of ``_method``. The form's ``method`` attribute must
    be set to POST when using this field:

    .. code-block:: html

        <form action="/my/target/route/" method="post">
            <!-- ... -->
            <input type="hidden" id="_method" name="_method" value="PUT" />
        </form>

    You need to explicitly enable this method override::

        use Symfony\Component\HttpFoundation\Request;

        Request::enableHttpMethodParameterOverride();
        $app->run();

You can also call ``match``, which will match all methods. This can be
restricted via the ``method`` method::

    $app->match('/blog', function () {
        // ...
    });

    $app->match('/blog', function () {
        // ...
    })
    ->method('PATCH');

    $app->match('/blog', function () {
        // ...
    })
    ->method('PUT|POST');

.. note::

    The order in which the routes are defined is significant. The first
    matching route will be used, so place more generic routes at the bottom.

Route Variables
~~~~~~~~~~~~~~~

As it has been shown before you can define variable parts in a route like
this::

    $app->get('/blog/{id}', function ($id) {
        // ...
    });

It is also possible to have more than one variable part, just make sure the
closure arguments match the names of the variable parts::

    $app->get('/blog/{postId}/{commentId}', function ($postId, $commentId) {
        // ...
    });

While it's not recommended, you could also do this (note the switched
arguments)::

    $app->get('/blog/{postId}/{commentId}', function ($commentId, $postId) {
        // ...
    });

You can also ask for the current Request and Application objects::

    $app->get('/blog/{id}', function (Application $app, Request $request, $id) {
        // ...
    });

.. note::

    Note for the Application and Request objects, Silex does the injection
    based on the type hinting and not on the variable name::

        $app->get('/blog/{id}', function (Application $foo, Request $bar, $id) {
            // ...
        });

Route Variable Converters
~~~~~~~~~~~~~~~~~~~~~~~~~

Before injecting the route variables into the controller, you can apply some
converters::

    $app->get('/user/{id}', function ($id) {
        // ...
    })->convert('id', function ($id) { return (int) $id; });

This is useful when you want to convert route variables to objects as it
allows to reuse the conversion code across different controllers::

    $userProvider = function ($id) {
        return new User($id);
    };

    $app->get('/user/{user}', function (User $user) {
        // ...
    })->convert('user', $userProvider);

    $app->get('/user/{user}/edit', function (User $user) {
        // ...
    })->convert('user', $userProvider);

The converter callback also receives the ``Request`` as its second argument::

    $callback = function ($post, Request $request) {
        return new Post($request->attributes->get('slug'));
    };

    $app->get('/blog/{id}/{slug}', function (Post $post) {
        // ...
    })->convert('post', $callback);

A converter can also be defined as a service. For example, here is a user
converter based on Doctrine ObjectManager::

    use Doctrine\Common\Persistence\ObjectManager;
    use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;

    class UserConverter
    {
        private $om;

        public function __construct(ObjectManager $om)
        {
            $this->om = $om;
        }

        public function convert($id)
        {
            if (null === $user = $this->om->find('User', (int) $id)) {
                throw new NotFoundHttpException(sprintf('User %d does not exist', $id));
            }

            return $user;
        }
    }

The service will now be registered in the application, and the
``convert()`` method will be used as converter (using the syntax
``service_name:method_name``)::

    $app['converter.user'] = function () {
        return new UserConverter();
    };

    $app->get('/user/{user}', function (User $user) {
        // ...
    })->convert('user', 'converter.user:convert');

Requirements
~~~~~~~~~~~~

In some cases you may want to only match certain expressions. You can define
requirements using regular expressions by calling ``assert`` on the
``Controller`` object, which is returned by the routing methods.

The following will make sure the ``id`` argument is a positive integer, since
``\d+`` matches any amount of digits::

    $app->get('/blog/{id}', function ($id) {
        // ...
    })
    ->assert('id', '\d+');

You can also chain these calls::

    $app->get('/blog/{postId}/{commentId}', function ($postId, $commentId) {
        // ...
    })
    ->assert('postId', '\d+')
    ->assert('commentId', '\d+');

Conditions
~~~~~~~~~~

Besides restricting route matching based on the HTTP method or parameter
requirements, you can set conditions on any part of the request by calling
``when`` on the ``Controller`` object, which is returned by the routing
methods::

    $app->get('/blog/{id}', function ($id) {
        // ...
    })
    ->when("request.headers.get('User-Agent') matches '/firefox/i'");

The ``when`` argument is a Symfony Expression_ , which means that you need to
add ``symfony/expression-language`` as a dependency of your project.

Default Values
~~~~~~~~~~~~~~

You can define a default value for any route variable by calling ``value`` on
the ``Controller`` object::

    $app->get('/{pageName}', function ($pageName) {
        // ...
    })
    ->value('pageName', 'index');

This will allow matching ``/``, in which case the ``pageName`` variable will
have the value ``index``.

Named Routes
~~~~~~~~~~~~

Some providers can make use of named routes. By default Silex will generate an
internal route name for you but you can give an explicit route name by calling
``bind``::

    $app->get('/', function () {
        // ...
    })
    ->bind('homepage');

    $app->get('/blog/{id}', function ($id) {
        // ...
    })
    ->bind('blog_post');

Controllers as Classes
~~~~~~~~~~~~~~~~~~~~~~

Instead of anonymous functions, you can also define your controllers as
methods. By using the ``ControllerClass::methodName`` syntax, you can tell
Silex to lazily create the controller object for you::

    $app->get('/', 'Acme\\Foo::bar');

    use Silex\Application;
    use Symfony\Component\HttpFoundation\Request;

    namespace Acme
    {
        class Foo
        {
            public function bar(Request $request, Application $app)
            {
                // ...
            }
        }
    }

This will load the ``Acme\Foo`` class on demand, create an instance and call
the ``bar`` method to get the response. You can use ``Request`` and
``Silex\Application`` type hints to get ``$request`` and ``$app`` injected.

It is also possible to :doc:`define your controllers as services
<providers/service_controller>`.

Global Configuration
--------------------

If a controller setting must be applied to **all** controllers (a converter, a
middleware, a requirement, or a default value), configure it on
``$app['controllers']``, which holds all application controllers::

    $app['controllers']
        ->value('id', '1')
        ->assert('id', '\d+')
        ->requireHttps()
        ->method('get')
        ->convert('id', function () { /* ... */ })
        ->before(function () { /* ... */ })
        ->when('request.isSecure() == true')
    ;

These settings are applied to already registered controllers and they become
the defaults for new controllers.

.. note::

    The global configuration does not apply to controller providers you might
    mount as they have their own global configuration (read the
    :doc:`dedicated chapter<organizing_controllers>` for more information).

Error Handlers
--------------

When an exception is thrown, error handlers allow you to display a custom
error page to the user. They can also be used to do additional things, such as
logging.

To register an error handler, pass a closure to the ``error`` method which
takes an ``Exception`` argument and returns a response::

    use Symfony\Component\HttpFoundation\Response;
    use Symfony\Component\HttpFoundation\Request;

    $app->error(function (\Exception $e, Request $request, $code) {
        return new Response('We are sorry, but something went terribly wrong.');
    });

You can also check for specific errors by using the ``$code`` argument, and
handle them differently::

    use Symfony\Component\HttpFoundation\Response;
    use Symfony\Component\HttpFoundation\Request;

    $app->error(function (\Exception $e, Request $request, $code) {
        switch ($code) {
            case 404:
                $message = 'The requested page could not be found.';
                break;
            default:
                $message = 'We are sorry, but something went terribly wrong.';
        }

        return new Response($message);
    });

You can restrict an error handler to only handle some Exception classes by
setting a more specific type hint for the Closure argument::

    use Symfony\Component\HttpFoundation\Request;

    $app->error(function (\LogicException $e, Request $request, $code) {
        // this handler will only handle \LogicException exceptions
        // and exceptions that extend \LogicException
    });

.. note::

    As Silex ensures that the Response status code is set to the most
    appropriate one depending on the exception, setting the status on the
    response won't work. If you want to overwrite the status code, set the
    ``X-Status-Code`` header::

        return new Response('Error', 404 /* ignored */, array('X-Status-Code' => 200));

If you want to use a separate error handler for logging, make sure you register
it with a higher priority than response error handlers, because once a response
is returned, the following handlers are ignored.

.. note::

    Silex ships with a provider for Monolog_ which handles logging of errors.
    Check out the *Providers* :doc:`chapter <providers/monolog>` for details.

.. tip::

    Silex comes with a default error handler that displays a detailed error
    message with the stack trace when **debug** is true, and a simple error
    message otherwise. Error handlers registered via the ``error()`` method
    always take precedence but you can keep the nice error messages when debug
    is turned on like this::

        use Symfony\Component\HttpFoundation\Response;
        use Symfony\Component\HttpFoundation\Request;

        $app->error(function (\Exception $e, Request $request, $code) use ($app) {
            if ($app['debug']) {
                return;
            }

            // ... logic to handle the error and return a Response
        });

The error handlers are also called when you use ``abort`` to abort a request
early::

    $app->get('/blog/{id}', function (Silex\Application $app, $id) use ($blogPosts) {
        if (!isset($blogPosts[$id])) {
            $app->abort(404, "Post $id does not exist.");
        }

        return new Response(...);
    });

You can convert errors to ``Exceptions``, check out the cookbook :doc:`chapter <cookbook/error_handler>` for details.

View Handlers
-------------

View Handlers allow you to intercept a controller result that is not a
``Response`` and transform it before it gets returned to the kernel.

To register a view handler, pass a callable (or string that can be resolved to a
callable) to the ``view()`` method. The callable should accept some sort of result
from the controller::

    $app->view(function (array $controllerResult) use ($app) {
        return $app->json($controllerResult);
    });

View Handlers also receive the ``Request`` as their second argument,
making them a good candidate for basic content negotiation::

    $app->view(function (array $controllerResult, Request $request) use ($app) {
        $acceptHeader = $request->headers->get('Accept');
        $bestFormat = $app['negotiator']->getBestFormat($acceptHeader, array('json', 'xml'));

        if ('json' === $bestFormat) {
            return new JsonResponse($controllerResult);
        }

        if ('xml' === $bestFormat) {
            return $app['serializer.xml']->renderResponse($controllerResult);
        }

        return $controllerResult;
    });

View Handlers will be examined in the order they are added to the application
and Silex will use type hints to determine if a view handler should be used for
the current result, continuously using the return value of the last view handler
as the input for the next.

.. note::

    You must ensure that Silex receives a ``Response`` or a string as the result of
    the last view handler (or controller) to be run.

Redirects
---------

You can redirect to another page by returning a ``RedirectResponse`` response,
which you can create by calling the ``redirect`` method::

    $app->get('/', function () use ($app) {
        return $app->redirect('/hello');
    });

This will redirect from ``/`` to ``/hello``.

Forwards
--------

When you want to delegate the rendering to another controller, without a
round-trip to the browser (as for a redirect), use an internal sub-request::

    use Symfony\Component\HttpFoundation\Request;
    use Symfony\Component\HttpKernel\HttpKernelInterface;

    $app->get('/', function () use ($app) {
        // forward to /hello
        $subRequest = Request::create('/hello', 'GET');

        return $app->handle($subRequest, HttpKernelInterface::SUB_REQUEST);
    });

.. tip::

    You can also generate the URI via the built-in URL generator::

        $request = Request::create($app['url_generator']->generate('hello'), 'GET');

There's some more things that you need to keep in mind though. In most cases you
will want to forward some parts of the current master request to the sub-request.
That includes: Cookies, server information, session.
Read more on :doc:`how to make sub-requests <cookbook/sub_requests>`.

JSON
----

If you want to return JSON data, you can use the ``json`` helper method.
Simply pass it your data, status code and headers, and it will create a JSON
response for you::

    $app->get('/users/{id}', function ($id) use ($app) {
        $user = getUser($id);

        if (!$user) {
            $error = array('message' => 'The user was not found.');

            return $app->json($error, 404);
        }

        return $app->json($user);
    });

Streaming
---------

It's possible to stream a response, which is important in cases when you don't
want to buffer the data being sent::

    $app->get('/images/{file}', function ($file) use ($app) {
        if (!file_exists(__DIR__.'/images/'.$file)) {
            return $app->abort(404, 'The image was not found.');
        }

        $stream = function () use ($file) {
            readfile($file);
        };

        return $app->stream($stream, 200, array('Content-Type' => 'image/png'));
    });

If you need to send chunks, make sure you call ``ob_flush`` and ``flush``
after every chunk::

    $stream = function () {
        $fh = fopen('http://www.example.com/', 'rb');
        while (!feof($fh)) {
            echo fread($fh, 1024);
            ob_flush();
            flush();
        }
        fclose($fh);
    };

Sending a file
--------------

If you want to return a file, you can use the ``sendFile`` helper method.
It eases returning files that would otherwise not be publicly available. Simply
pass it your file path, status code, headers and the content disposition and it
will create a ``BinaryFileResponse`` response for you::

    $app->get('/files/{path}', function ($path) use ($app) {
        if (!file_exists('/base/path/' . $path)) {
            $app->abort(404);
        }

        return $app->sendFile('/base/path/' . $path);
    });

To further customize the response before returning it, check the API doc for
`Symfony\Component\HttpFoundation\BinaryFileResponse
<http://api.symfony.com/master/Symfony/Component/HttpFoundation/BinaryFileResponse.html>`_::

    return $app
        ->sendFile('/base/path/' . $path)
        ->setContentDisposition(ResponseHeaderBag::DISPOSITION_ATTACHMENT, 'pic.jpg')
    ;

Traits
------

Silex comes with PHP traits that define shortcut methods.

Almost all built-in service providers have some corresponding PHP traits. To
use them, define your own Application class and include the traits you want::

    use Silex\Application;

    class MyApplication extends Application
    {
        use Application\TwigTrait;
        use Application\SecurityTrait;
        use Application\FormTrait;
        use Application\UrlGeneratorTrait;
        use Application\SwiftmailerTrait;
        use Application\MonologTrait;
        use Application\TranslationTrait;
    }

You can also define your own Route class and use some traits::

    use Silex\Route;

    class MyRoute extends Route
    {
        use Route\SecurityTrait;
    }

To use your newly defined route, override the ``$app['route_class']``
setting::

    $app['route_class'] = 'MyRoute';

Read each provider chapter to learn more about the added methods.

Security
--------

Make sure to protect your application against attacks.

Escaping
~~~~~~~~

When outputting any user input, make sure to escape it correctly to prevent
Cross-Site-Scripting attacks.

* **Escaping HTML**: PHP provides the ``htmlspecialchars`` function for this.
  Silex provides a shortcut ``escape`` method::

      use Symfony\Component\HttpFoundation\Request;

      $app->get('/name', function (Request $request, Silex\Application $app) {
          $name = $request->get('name');

          return "You provided the name {$app->escape($name)}.";
      });

  If you use the Twig template engine, you should use its escaping or even
  auto-escaping mechanisms. Check out the *Providers* :doc:`chapter <providers/twig>` for details.

* **Escaping JSON**: If you want to provide data in JSON format you should
  use the Silex ``json`` function::

      use Symfony\Component\HttpFoundation\Request;

      $app->get('/name.json', function (Request $request, Silex\Application $app) {
          $name = $request->get('name');

          return $app->json(array('name' => $name));
      });

.. _Silex Skeleton: http://github.com/silexphp/Silex-Skeleton
.. _Composer: http://getcomposer.org/
.. _Request: http://api.symfony.com/master/Symfony/Component/HttpFoundation/Request.html
.. _Response: http://api.symfony.com/master/Symfony/Component/HttpFoundation/Response.html
.. _Monolog: https://github.com/Seldaek/monolog
.. _Expression: https://symfony.com/doc/current/book/routing.html#completely-customized-route-matching-with-conditions