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Merge pull request symfony#3232 from symfony/expression-framework-container
[symfony#3022] Adding service container expression language details
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‎book/includes/_service_container_my_mailer.rst.inc

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.. configuration-block::
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.. code-block:: yaml
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# app/config/config.yml
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services:
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my_mailer:
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class: Acme\HelloBundle\Mailer
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arguments: [sendmail]
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.. code-block:: xml
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<!-- app/config/config.xml -->
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<?xml version="1.0" encoding="UTF-8" ?>
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<container xmlns="http://symfony.com/schema/dic/services"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://symfony.com/schema/dic/services
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http://symfony.com/schema/dic/services/services-1.0.xsd"
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>
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<services>
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<service id="my_mailer" class="Acme\HelloBundle\Mailer">
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<argument>sendmail</argument>
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</service>
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</services>
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</container>
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.. code-block:: php
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// app/config/config.php
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use Symfony\Component\DependencyInjection\Definition;
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$container->setDefinition('my_mailer', new Definition(
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'Acme\HelloBundle\Mailer',
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array('sendmail')
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));

‎book/service_container.rst

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@@ -103,40 +103,7 @@ for you. In order for this to work, you must *teach* the container how to
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create the ``Mailer`` service. This is done via configuration, which can
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be specified in YAML, XML or PHP:
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.. configuration-block::
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.. code-block:: yaml
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# app/config/config.yml
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services:
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my_mailer:
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class: Acme\HelloBundle\Mailer
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arguments: [sendmail]
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.. code-block:: xml
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<!-- app/config/config.xml -->
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<?xml version="1.0" encoding="UTF-8" ?>
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<container xmlns="http://symfony.com/schema/dic/services"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
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<services>
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<service id="my_mailer" class="Acme\HelloBundle\Mailer">
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<argument>sendmail</argument>
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</service>
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</services>
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</container>
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.. code-block:: php
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// app/config/config.php
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use Symfony\Component\DependencyInjection\Definition;
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$container->setDefinition('my_mailer', new Definition(
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'Acme\HelloBundle\Mailer',
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array('sendmail')
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));
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.. include includes/_service_container_my_mailer.rst.inc
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.. note::
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this dependency in the service container, the container takes care of all
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the work of instantiating the classes.
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Using the Expression Language
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. versionadded:: 2.4
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The Expression Language functionality was introduced in Symfony 2.4.
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The service container also supports an "expression" that allows you to inject
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very specific values into a service.
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For example, suppose you have a third service (not shown here), called ``mailer_configuration``,
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which has a ``getMailerMethod()`` method on it, which will return a string
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like ``sendmail`` based on some configuration. Remember that the first argument
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to the ``my_mailer`` service is the simple string ``sendmail``:
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.. include includes/_service_container_my_mailer.rst.inc
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But instead of hardcoding this, how could we get this value from the ``getMailerMethod()``
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of the new ``mailer_configuration`` service? One way is to use an expression:
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.. configuration-block::
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.. code-block:: yaml
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# app/config/config.yml
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services:
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my_mailer:
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class: Acme\HelloBundle\Mailer
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arguments: ["@=service('mailer_configuration').getMailerMethod()"]
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.. code-block:: xml
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<!-- app/config/config.xml -->
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<?xml version="1.0" encoding="UTF-8" ?>
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<container xmlns="http://symfony.com/schema/dic/services"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://symfony.com/schema/dic/services
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http://symfony.com/schema/dic/services/services-1.0.xsd"
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>
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<services>
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<service id="my_mailer" class="Acme\HelloBundle\Mailer">
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<argument type="expression">service('mailer_configuration').getMailerMethod()</argument>
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</service>
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</services>
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</container>
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.. code-block:: php
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// app/config/config.php
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use Symfony\Component\DependencyInjection\Definition;
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use Symfony\Component\ExpressionLanguage\Expression;
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$container->setDefinition('my_mailer', new Definition(
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'Acme\HelloBundle\Mailer',
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array(new Expression('service("mailer_configuration").getMailerMethod()'))
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));
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To learn more about the expression language syntax, see :doc:`/components/expression_language/syntax`.
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In this context, you have access to 2 functions:
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* ``service`` - returns a given service (see the example above);
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* ``parameter`` - returns a specific parameter value (syntax is just like ``service``)
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You also have access to the :class:`Symfony\\Component\\DependencyInjection\\ContainerBuilder`
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via a ``container`` variable. Here's another example:
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.. configuration-block::
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.. code-block:: yaml
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services:
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my_mailer:
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class: Acme\HelloBundle\Mailer
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arguments: ["@=container.hasParameter('some_param') ? parameter('some_param') : 'default_value'"]
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.. code-block:: xml
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<?xml version="1.0" encoding="UTF-8" ?>
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<container xmlns="http://symfony.com/schema/dic/services"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://symfony.com/schema/dic/services
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http://symfony.com/schema/dic/services/services-1.0.xsd"
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>
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<services>
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<service id="my_mailer" class="Acme\HelloBundle\Mailer">
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<argument type="expression">@=container.hasParameter('some_param') ? parameter('some_param') : 'default_value'</argument>
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</service>
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</services>
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</container>
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.. code-block:: php
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use Symfony\Component\DependencyInjection\Definition;
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use Symfony\Component\ExpressionLanguage\Expression;
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$container->setDefinition('my_mailer', new Definition(
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'Acme\HelloBundle\Mailer',
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array(new Expression(
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"@=container.hasParameter('some_param') ? parameter('some_param') : 'default_value'"
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))
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));
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Expressions can be used in ``parameters``, ``arguments``, ``properties``,
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as arguments with ``configurator`` and as arguments to ``calls`` (method calls).
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Optional Dependencies: Setter Injection
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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