The Asset component manages URL generation and versioning of web assets such

as CSS stylesheets, JavaScript files and image files.

For example:

.. code-block:: html

The ``Packages`` class allows to define a default package, which will be applied

application defines a package named ``img`` to serve images from an external

domain and a ``doc`` package to avoid repeating long paths when linking to a

document inside a template::

The Symfony Framework uses the built-in

:class:`Symfony\\Component\\HttpKernel\\Controller\\ControllerResolver`

mentioned below). This class leverages the information that was placed

on the ``Request`` object's ``attributes`` property during the ``RouterListener``.

5) Calling the Controller

The job of the controller is to build the response for the given resource.

This could be an HTML page, a JSON string or anything else. Unlike every

The name of each of the "kernel" events is defined as a constant on the

:class:`Symfony\\Component\\HttpKernel\\KernelEvents` class. Additionally, each

This object contains information about the current state of the system and

each event has their own event object:

In addition to the "main" request that's sent into ``HttpKernel::handle()``,

any other request, but typically serves to render just one small portion of

a page instead of a full page. You'll most commonly make sub-requests from

your controller (or perhaps from inside a template, that's being rendered by

This creates another full request-response cycle where this new ``Request`` is

transformed into a ``Response``. The only difference internally is that some

listeners (e.g. security) may only act upon the master request. Each listener

whose :method:`Symfony\\Component\\HttpKernel\\Event\\KernelEvent::isMasterRequest`

can be used to check if the current request is a "master" or "sub" request.

.. tip::

If you don't release the lock explicitly, it will be released automatically

across several requests. To disable the automatic release behavior, set the

third argument of the ``createLock()`` method to ``false``.

The ``Key`` contains the state of the ``Lock`` and can be serialized. This

allows the user to begin a long job in a process by acquiring the lock, and

Automatically Releasing The Lock

an implementation detail that will be important when sharing Locks between

processes. In the example below, ``pcntl_fork()`` creates two processes and the

Lock will be released automatically as soon as one process finishes::

By using the file system, this ``Store`` is reliable as long as concurrent

Processes must run on the same machine, virtual machine or container.

The absolute path to the directory must remain the same. Be careful of symlinks

that could change at anytime: Capistrano and blue/green deployment often use

.. caution::

All concurrent processes must use the same physical file system by running

By definition, usage of ``FlockStore`` in an HTTP context is incompatible

with multiple front servers, unless to ensure that the same resource will

The way Memcached works is to store items in memory. That means that by using

the :ref:`MemcachedStore <lock-store-memcached>` the locks are not persisted

If the Memcached service or the machine hosting it restarts, every lock would

be lost without notifying the running processes.

.. caution::

In a cluster configured with multiple primaries, ensure writes are

.. caution::

The way Redis works is to store items in memory. That means that by using

the :ref:`RedisStore <lock-store-redis>` the locks are not persisted

If the Redis service or the machine hosting it restarts, every locks would

be lost without notifying the running processes.

CombinedStore

mistake to think that the lock mechanism will be more reliable. This is wrong.

The ``CombinedStore`` will be, at best, as reliable as the least reliable of

all managed stores. As soon as one managed store returns erroneous information,

* A high-level API based on the :class:`Symfony\\Component\\Mime\\Email` class

to quickly create email messages with all the common features;

* A low-level API based on the :class:`Symfony\\Component\\Mime\\Message` class

Usage

:doc:`Mailer component </mailer>` to actually send them.

Twig Integration

This way, the ``$value`` argument will receive the previously normalized

value, otherwise you can prepend the new normalizer by passing ``true`` as

third argument.

to set the port to ``465`` if SSL is used and to ``25`` otherwise.

You can implement this feature by passing a closure as the default value of

these options, you can return the desired default value::

.. note::

The closure is only executed if the ``port`` option isn't set by the user

A previously set default value can be accessed by adding a second argument to

the closure::

Using Features From the OS Shell

saves you from any escaping and allows sending signals seamlessly

(e.g. to stop processes while they run)::

The :method:`Symfony\\Component\\Process\\InputStream::write` method accepts scalars,

you need to explicitly call the :method:`Symfony\\Component\\Process\\InputStream::close`

method when you are done writing to the standard input of the subprocess.

The PropertyAccess component checks for methods called ``add<SingularOfThePropertyName>()``

and ``remove<SingularOfThePropertyName>()``. Both methods must be defined.

For instance, in the previous example, the component looks for the ``addChild()``

`The Inflector component`_ is used to find the singular of a property name.

If available, *adder* and *remover* methods have priority over a *setter* method.

You can also implement

:class:`Symfony\\Component\\Serializer\\NameConverter\\AdvancedNameConverterInterface`

.. _using-camelized-method-names-for-underscored-attributes:

and ``$options = ['csv_headers' => ['a', 'b', 'c']]``

then ``serialize($data, 'csv', $options)`` returns

``a,b,c\n1,2,3`` ``[]``, inferred from input data's keys

with a ``\t`` character

``as_collection`` Always returns results as a collection, even if only ``true``

one line is decoded.

Instances of ``ArrayObject``, ``ArrayIterator`` and ``SplObjectHash`` can be

created by using the special ``"\0"`` property name to define their internal value::