Merge pull request #992 from ChrisTickner/app_global_variable

[Book] [Templating] Added app global variable section

Author: weaverryan

book/templating.rst

@@ -871,6 +871,45 @@ is by default "web").
 The end result is a page that includes both the ``main.css`` and ``contact.css``
 stylesheets.
 
+Global Template Variables
+-------------------------
+
+During each request, Symfony2 will set a global template variable ``app``
+in both Twig and PHP template engines by default.  The ``app`` variable
+is a :class:`Symfony\\Bundle\\FrameworkBundle\\Templating\\GlobalVariables`
+instance which will give you access to some application specific variables
+automatically:
+
+* ``app.security`` - The security context.
+* ``app.user`` - The current user object.
+* ``app.request`` - The request object.
+* ``app.session`` - The session object.
+* ``app.environment`` - The current environment (dev, prod, etc).
+* ``app.debug`` - True if in debug mode. False otherwise.
+
+.. configuration-block::
+
+    .. code-block:: html+jinja
+
+        <p>Username: {{ app.user.username }}</p>
+        {% if app.debug %}
+            <p>Request method: {{ app.request.method }}</p>
+            <p>Application Environment: {{ app.environment }}</p>
+        {% endif %}
+
+    .. code-block:: html+php
+
+        <p>Username: <?php echo $app->getUser()->getUsername() ?></p>
+        <?php if ($app->getDebug()): ?>
+            <p>Request method: <?php echo $app->getRequest()->getMethod() ?></p>
+            <p>Application Environment: <?php echo $app->getEnvironment() ?></p>
+        <?php endif; ?>
+
+.. tip::
+
+    You can add your own global template variables. See the cookbook example
+    on :doc:`Global Variables</cookbook/templating/global_variables>`.
+
 .. index::
    single: Templating; The templating service