global_variables.rst

.. index::
   single: Templating; Global variables

How to Inject Variables into all Templates (i.e. Global Variables)

Sometimes you want a variable to be accessible to all the templates you use. This is possible inside your app/config/config.yml file:

.. configuration-block::

    .. code-block:: yaml

        # app/config/config.yml
        twig:
            # ...
            globals:
                ga_tracking: UA-xxxxx-x

    .. code-block:: xml

        <!-- app/config/config.xml -->
        <twig:config ...>
            <!-- ... -->
            <twig:global key="ga_tracking">UA-xxxxx-x</twig:global>
        </twig:config>

    .. code-block:: php

        // app/config/config.php
        $container->loadFromExtension('twig', array(
             // ...
             'globals' => array(
                 'ga_tracking' => 'UA-xxxxx-x',
             ),
        ));

Now, the variable ga_tracking is available in all Twig templates:

<p>The google tracking code is: {{ ga_tracking }}</p>

It's that easy!

Using Service Container Parameters

You can also take advantage of the built-in :ref:`book-service-container-parameters` system, which lets you isolate or reuse the value:

# app/config/parameters.yml
parameters:
    ga_tracking: UA-xxxxx-x

.. configuration-block::

    .. code-block:: yaml

        # app/config/config.yml
        twig:
            globals:
                ga_tracking: "%ga_tracking%"

    .. code-block:: xml

        <!-- app/config/config.xml -->
        <twig:config ...>
            <twig:global key="ga_tracking">%ga_tracking%</twig:global>
        </twig:config>

    .. code-block:: php

        // app/config/config.php
        $container->loadFromExtension('twig', array(
             'globals' => array(
                 'ga_tracking' => '%ga_tracking%',
             ),
        ));

The same variable is available exactly as before.

Referencing Services

Instead of using static values, you can also set the value to a service. Whenever the global variable is accessed in the template, the service will be requested from the service container and you get access to that object.

Note

The service is not loaded lazily. In other words, as soon as Twig is loaded, your service is instantiated, even if you never use that global variable.

To define a service as a global Twig variable, prefix the string with @. This should feel familiar, as it's the same syntax you use in service configuration.

.. configuration-block::

    .. code-block:: yaml

        # app/config/config.yml
        twig:
            # ...
            globals:
                user_management: "@acme_user.user_management"

    .. code-block:: xml

        <!-- app/config/config.xml -->
        <twig:config ...>
            <!-- ... -->
            <twig:global key="user_management">@acme_user.user_management</twig:global>
        </twig:config>

    .. code-block:: php

        // app/config/config.php
        $container->loadFromExtension('twig', array(
             // ...
             'globals' => array(
                 'user_management' => '@acme_user.user_management',
             ),
        ));

Using a Twig Extension

If the global variable you want to set is more complicated - say an object - then you won't be able to use the above method. Instead, you'll need to create a :ref:`Twig Extension <reference-dic-tags-twig-extension>` and return the global variable as one of the entries in the getGlobals method.