1. Powerful and flexible
templates with Twig
Michael Peacock, PHPNE December
2012

2. @michaelpeacock
Head Developer @groundsix
Author
Occasional conference speaker
michaelpeacock.co.uk
twitter.com/michaelpeacock

3. Installation
Create a composer.json file
{
"require": {
"twig/twig": "1.*"
}
}
Download composer
curl -s http://getcomposer.org/installer | php
Run composer to install twig
php composer.phar install

4. Setup
$loader = new Twig_Loader_Filesystem(__DIR__ . '/templates/');
// ideally sits in a dependency injection container
$twig = new Twig_Environment($loader, array(
'cache' => __DIR__ . '/cache/templates',
));

5. Basic usage
$template = $twig->loadTemplate('mytemplate.html.twig');
echo $template->render($array_of_template_variables);
exit;

6. Template variables
Associative array
Keys are used to access the data in the
templates
Values are displayed / rendered in the
templates
Values can be:
Arrays
Objects
Data

7. Base templates
A base template defines “blocks” which can be
overridden by other templates
The block can contain default content;
overriding is optional
Makes it easy to change small amounts of a
base template on only a few specific pages

8. Blocks
{% block content %}
{% endblock %}
{% block content %}
<p>This is some default content which will be
displayed if the template is
used directly or if it isn't overriden by another
template</p>
{% endblock %}

9. Extending base
Extend your base template
{% include 'base.twig.html' %}
Override your blocks
{% block content %}
<p>This is overriding the base template</p>
{% endblock %}

10. Includes
{% include 'another_template.html.twig' %}
{% include template_name_in_variable %}
{% include template_from_string(variable_containing_twig) %}

11. A note on context
By default all included templates and base
templates inherit their template variables from
the template you are rendering
You can change this by passing a list of
variables when including a template
{% include 'another_template.html.twig' with other_variables only %}
You can also pass more variables by omitting
the only keyword

12. Printing variables
Output is automatically escaped
{{my_variable}}
But you can tell twig to not escape some data
(using a filter, which we will look at shortly)
{{my_variable|raw}}

13. Dynamic Magic
{{ check if }} is an array and bar a valid element;
foo.bar foo
if not, and if foo is an object, check that bar is a valid
property;
if not, and if foo is an object, check that bar is a valid
method (even if bar is the constructor - use
__construct() instead);
if not, and if foo is an object, check that getBar is a valid
method;
if not, and if foo is an object, check that isBar is a valid
method;
if not, return a null value.
Source: http://twig.sensiolabs.org/doc/templates.html#variables

14. Explicit types
You can also instruct twig to call a method on
an object or access a property of an array as
opposed to relying on the dynamic magic
{{object.method()}}
{{array[‘variable’]}}

15. Setting variables
You can also create variables on-the-fly
{% set new_variable = ‘variable’ %}
Useful when working with objects or arrays, as
you can pull out data, manipulate it and use it as
a variable in its own right

16. Conditions
{% if logged_in_user is not null %}
<p>Welcome logged_in_user.name. <a href="/logout">Logout</a></p>
{% else %}
<p><a href="/login">Login</a></p>
{% endif %}

17. Supported comparisons
==
!=
<
>
>=
<=

18. Ternary operators
{{ logged_in ? logged_in_username : 'guest' }}

19. Loops
<ul>
{% for item in array_or_iterable_object %}
<li>item.getName</li>
{% else %}
<li>No results found</li>
{% endfor %}
</ul>

20. Loop data
Iteration of a loop (1 indexed)
{{loop.index}}
Parent loop iteration (1 indexed)
{{loop.parent.loop.index}}
Other information
loop.index0 (0 indexed iteration)
loop.revindex (reversed index)
loop.first (true if first iteration)
loop.last (truue if last iteration)
loop.length

21. Concatenation
~

22. Filters
Many of them are twig wrappers for PHP functions
Date: {{ article.publication_date|date("d/m/Y") }}
Number format {{500123.0123|number_format}}
Url encode {{variable|url_encode()}}
Length (of string or items in array) {{variable|
length}}
You can use multiple filters e.g. {{var|trans|raw}}
Lots more!
http://twig.sensiolabs.org/doc/filters/index.html

23. Custom filters
Create a function
First parameter is what appears before the filter, other parameters
are set when you use the filter if required (ideally, these should be
optional)
function twig_filter_gravatar($email, $default='mm', $size=30)
{
return "http://www.gravatar.com/avatar/" . md5(strtolower(trim($email))) . "?d=" .
urlencode($default) . "&s=" . $size;
}
Add the filter
$twig->addFilter('gravatar', new Twig_Filter_Function('twig_filter_gravatar'));
Use the filter
{{user.getEmail|gravatar}}
Unfortunately closures can’t be used yet

24. Twig
Powerful, flexible templates
Easy to build and extend
Syntax thats friendly for designers
Allows some level of control in the templates
A bit of a double edged sword - with great
template flexibility comes great responsibility!
http://twig.sensiolabs.org/