Powerful and flexible templates with Twig

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

@michaelpeacock

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

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

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',
));

Basic usage

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

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

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

Blocks

{% block content %}
{% endblock %}

{% block content %}
This is some default content which will be
displayed if the template is
used directly or if it isn't overriden by another
template
{% endblock %}

Extending base

Extend your base template

{% include 'base.twig.html' %}

Override your blocks

{% block content %}
This is overriding the base template
{% endblock %}

Includes

{% include 'another_template.html.twig' %}

{% include template_name_in_variable %}

{% include template_from_string(variable_containing_twig) %}

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

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}}

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

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’]}}

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

Conditions

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

Supported comparisons

==
!=
<
>
>=
<=

Ternary operators

{{ logged_in ? logged_in_username : 'guest' }}

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

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

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

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

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/

Powerful and flexible templates with Twig

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