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! 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.

More Complex Global Variables

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.