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Twig for Template Designers

This document describes the syntax and semantics of the template engine and will be most useful as reference to those creating Twig templates.

Synopsis

A template is simply a text file. It can generate any text-based format (HTML, XML, CSV, LaTeX, etc.). It doesn't have a specific extension, .html or .xml are just fine.

A template contains variables or expressions, which get replaced with values when the template is evaluated, and tags, which control the logic of the template.

Below is a minimal template that illustrates a few basics. We will cover the details later in that document:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang="en">
  <head>
    <title>My Webpage</title>
  </head>
  <body>
    <ul id="navigation">
    {% for item in navigation %}
      <li><a href="{{ item.href }}">{{ item.caption }}</a></li>
    {% endfor %}
    </ul>

    <h1>My Webpage</h1>
    {{ a_variable }}
  </body>
</html>

There are two kinds of delimiters: {% ... %} and {{ ... }}. The first one is used to execute statements such as for-loops, the latter prints the result of an expression to the template.

IDEs Integration

Modern IDEs support syntax highlighting and auto-completion for a large range of languages. As Twig syntax is quite similar to Jinja and Django templates, IDEs that support these two Python templating systems should also support Twig.

If you use Textmate, you can use the Jinja bundle or the Django one.

If you use Vim, you can use the Jinja syntax plugin.

Variables

The application passes variables to the templates you can mess around in the template. Variables may have attributes or elements on them you can access too. How a variable looks like, heavily depends on the application providing those.

You can use a dot (.) to access attributes of a variable, alternative the so-called "subscript" syntax ([]) can be used. The following lines do the same:

{{ foo.bar }}
{{ foo['bar'] }}

Note

It's important to know that the curly braces are not part of the variable but the print statement. If you access variables inside tags don't put the braces around.

If a variable or attribute does not exist you will get back a null value (which can be tested with the none expression).

Implementation

For convenience sake foo.bar does the following things on the PHP layer:

  • check if foo is an array and bar a valid element;
  • 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.

foo['bar'] on the other hand works mostly the same with the a small difference in the order:

  • check if foo is an array and bar a valid element;
  • if not, return a null value.

Using the alternative syntax is also useful to dynamically get attributes from arrays:

foo[bar]

Twig always references the following variables:

  • _self: references the current template;
  • _context: references the current context;
  • _charset: references the current charset.

Filters

Variables can by modified by filters. Filters are separated from the variable by a pipe symbol (|) and may have optional arguments in parentheses. Multiple filters can be chained. The output of one filter is applied to the next.

{{ name|striptags|title }} for example will remove all HTML tags from the name and title-cases it. Filters that accept arguments have parentheses around the arguments, like a function call. This example will join a list by commas: {{ list|join(', ') }}.

The built-in filters section below describes all the built-in filters.

Comments

To comment-out part of a line in a template, use the comment syntax {# ... #}. This is useful to comment out parts of the template for debugging or to add information for other template designers or yourself:

{# note: disabled template because we no longer use this
    {% for user in users %}
        ...
    {% endfor %}
#}

Whitespace Control

The first newline after a template tag is removed automatically (like in PHP.) Whitespace is not further modified by the template engine, so each whitespace (spaces, tabs, newlines etc.) is returned unchanged.

Use the spaceless tag to remove whitespace between HTML tags:

{% spaceless %}
    <div>
        <strong>foo</strong>
    </div>
{% endspaceless %}

{# output will be <div><strong>foo</strong></div> #}

Escaping

It is sometimes desirable or even necessary to have Twig ignore parts it would otherwise handle as variables or blocks. For example if the default syntax is used and you want to use {{ as raw string in the template and not start a variable you have to use a trick.

The easiest way is to output the variable delimiter ({{) by using a variable expression:

{{ '{{' }}

For bigger sections it makes sense to mark a block raw. For example to put Twig syntax as example into a template you can use this snippet:

{% raw %}
  <ul>
  {% for item in seq %}
    <li>{{ item }}</li>
  {% endfor %}
  </ul>
{% endraw %}

Template Inheritance

The most powerful part of Twig is template inheritance. Template inheritance allows you to build a base "skeleton" template that contains all the common elements of your site and defines blocks that child templates can override.

Sounds complicated but is very basic. It's easiest to understand it by starting with an example.

Base Template

This template, which we'll call base.html, defines a simple HTML skeleton document that you might use for a simple two-column page. It's the job of "child" templates to fill the empty blocks with content:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang="en">
<head>
  {% block head %}
    <link rel="stylesheet" href="style.css" />
    <title>{% block title %}{% endblock %} - My Webpage</title>
  {% endblock %}
</head>
<body>
  <div id="content">{% block content %}{% endblock %}</div>
  <div id="footer">
    {% block footer %}
      &copy; Copyright 2009 by <a href="http://domain.invalid/">you</a>.
    {% endblock %}
  </div>
</body>
</html>

In this example, the {% block %} tags define four blocks that child templates can fill in. All the block tag does is to tell the template engine that a child template may override those portions of the template.

Child Template

A child template might look like this:

{% extends "base.html" %}

{% block title %}Index{% endblock %}
{% block head %}
  {{ parent() }}
  <style type="text/css">
    .important { color: #336699; }
  </style>
{% endblock %}
{% block content %}
  <h1>Index</h1>
  <p class="important">
    Welcome on my awesome homepage.
  </p>
{% endblock %}

The {% extends %} tag is the key here. It tells the template engine that this template "extends" another template. When the template system evaluates this template, first it locates the parent. The extends tag should be the first tag in the template.

The filename of the template depends on the template loader. For example the Twig_Loader_Filesystem allows you to access other templates by giving the filename. You can access templates in subdirectories with a slash:

{% extends "layout/default.html" %}

But this behavior can depend on the application embedding Twig. Note that since the child template doesn't define the footer block, the value from the parent template is used instead.

You can't define multiple {% block %} tags with the same name in the same template. This limitation exists because a block tag works in "both" directions. That is, a block tag doesn't just provide a hole to fill - it also defines the content that fills the hole in the parent. If there were two similarly-named {% block %} tags in a template, that template's parent wouldn't know which one of the blocks' content to use.

If you want to print a block multiple times you can however use the block function:

<title>{% block title %}{% endblock %}</title>
<h1>{{ block('title') }}</h1>
{% block body %}{% endblock %}

Like PHP, Twig does not support multiple inheritance. So you can only have one extends tag called per rendering.

Parent Blocks

It's possible to render the contents of the parent block by using the parent function. This gives back the results of the parent block:

{% block sidebar %}
  <h3>Table Of Contents</h3>
  ...
  {{ parent() }}
{% endblock %}

Named Block End-Tags

Twig allows you to put the name of the block after the end tag for better readability:

{% block sidebar %}
  {% block inner_sidebar %}
      ...
  {% endblock inner_sidebar %}
{% endblock sidebar %}

However the name after the endblock word must match the block name.

Block Nesting and Scope

Blocks can be nested for more complex layouts. Per default, blocks have access to variables from outer scopes:

{% for item in seq %}
  <li>{% block loop_item %}{{ item }}{% endblock %}</li>
{% endfor %}

Block Shortcuts

For blocks with few content, it's possible to have a shortcut syntax. The following constructs do the same:

{% block title %}
  {{ page_title|title }}
{% endblock %}
{% block title page_title|title %}

Dynamic Inheritance

Twig supports dynamic inheritance by using a variable as the base template:

{% extends some_var %}

If the variable evaluates to a Twig_Template object, Twig will use it as the parent template:

// {% extends layout %}

$layout = $twig->loadTemplate('some_layout_template.twig');

$twig->display('template.twig', array('layout' => $layout));

Conditional Inheritance

As a matter of fact, the template name can be any valid expression. So, it's also possible to make the inheritance mechanism conditional:

{% extends standalone ? "minimum.html" : "base.html" %}

In this example, the template will extend the "minimum.html" layout template if the standalone variable evaluates to true, and "base.html" otherwise.

Import Context Behavior

Per default included templates are passed the current context.

The context that is passed to the included template includes variables defined in the template:

{% for box in boxes %}
  {% include "render_box.html" %}
{% endfor %}

The included template render_box.html is able to access box.

HTML Escaping

When generating HTML from templates, there's always a risk that a variable will include characters that affect the resulting HTML. There are two approaches: manually escaping each variable or automatically escaping everything by default.

Twig supports both, automatic escaping is enabled by default.

Note

Automatic escaping is only supported if the escaper extension has been enabled (which is the default).

Working with Manual Escaping

If manual escaping is enabled it's your responsibility to escape variables if needed. What to escape? If you have a variable that may include any of the following chars (>, <, &, or ") you have to escape it unless the variable contains well-formed and trusted HTML. Escaping works by piping the variable through the |e filter: {{ user.username|e }}.

Working with Automatic Escaping

Whether automatic escaping is enabled or not, you can mark a section of a template to be escaped or not by using the autoescape tag:

{% autoescape true %}
  Everything will be automatically escaped in this block
{% endautoescape %}

{% autoescape false %}
  Everything will be outputed as is in this block
{% endautoescape %}

{% autoescape true js %}
  Everything will be automatically escaped in this block
  using the js escaping strategy
{% endautoescape %}

When automatic escaping is enabled everything is escaped by default except for values explicitly marked as safe. Those can be marked in the template by using the |raw filter.

Functions returning template data (like macros and parent) always return safe markup.

Note

Twig is smart enough to not escape an already escaped value by the escape filter.

Note

The chapter for developers give more information about when and how automatic escaping is applied.

List of Control Structures

A control structure refers to all those things that control the flow of a program - conditionals (i.e. if/elseif/else), for-loops, as well as things like blocks. Control structures appear inside {% ... %} blocks.

For

Loop over each item in a sequence. For example, to display a list of users provided in a variable called users:

<h1>Members</h1>
<ul>
  {% for user in users %}
    <li>{{ user.username|e }}</li>
  {% endfor %}
</ul>

Note

A sequence can be either an array or an object implementing the Traversable interface.

If you do need to iterate over a sequence of numbers, you can use the .. operator:

{% for i in 0..10 %}
  * {{ i }}
{% endfor %}

The above snippet of code would print all numbers from 0 to 10.

It can be also useful with letters:

{% for letter in 'a'..'z' %}
  * {{ letter }}
{% endfor %}

The .. operator can take any expression at both sides:

{% for letter in 'a'|upper..'z'|upper %}
  * {{ letter }}
{% endfor %}

If you need a step different from 1, you can use the range function instead:

{% for i in range(0, 10, 2) %}
  * {{ i }}
{% endfor %}

Inside of a for loop block you can access some special variables:

Variable Description
loop.index The current iteration of the loop. (1 indexed)
loop.index0 The current iteration of the loop. (0 indexed)
loop.revindex The number of iterations from the end of the loop (1 indexed)
loop.revindex0 The number of iterations from the end of the loop (0 indexed)
loop.first True if first iteration
loop.last True if last iteration
loop.length The number of items in the sequence
loop.parent The parent context

Note

The loop.length, loop.revindex, loop.revindex0, and loop.last variables are only available for PHP arrays, or objects that implement the Countable interface.

Note

Unlike in PHP it's not possible to break or continue in a loop.

If no iteration took place because the sequence was empty, you can render a replacement block by using else:

<ul>
  {% for user in users %}
    <li>{{ user.username|e }}</li>
  {% else %}
    <li><em>no user found</em></li>
  {% endfor %}
</ul>

By default, a loop iterates over the values of the sequence. You can iterate on keys by using the keys filter:

<h1>Members</h1>
<ul>
  {% for key in users|keys %}
    <li>{{ key }}</li>
  {% endfor %}
</ul>

You can also access both keys and values:

<h1>Members</h1>
<ul>
  {% for key, user in users %}
    <li>{{ key }}: {{ user.username|e }}</li>
  {% endfor %}
</ul>

If

The if statement in Twig is comparable with the if statements of PHP. In the simplest form you can use it to test if a variable is not empty:

{% if users %}
  <ul>
    {% for user in users %}
      <li>{{ user.username|e }}</li>
    {% endfor %}
  </ul>
{% endif %}

Note

If you want to test if the variable is defined, use if users is defined instead.

For multiple branches elseif and else can be used like in PHP. You can use more complex expressions there too:

{% if kenny.sick %}
    Kenny is sick.
{% elseif kenny.dead %}
    You killed Kenny!  You bastard!!!
{% else %}
    Kenny looks okay --- so far
{% endif %}

Macros

Macros are comparable with functions in regular programming languages. They are useful to put often used HTML idioms into reusable elements to not repeat yourself.

Here is a small example of a macro that renders a form element:

{% macro input(name, value, type, size) %}
    <input type="{{ type|default('text') }}" name="{{ name }}" value="{{ value|e }}" size="{{ size|default(20) }}" />
{% endmacro %}

Macros differs from native PHP functions in a few ways:

  • Default argument values are defined by using the default filter in the macro body;
  • Arguments of a macro are always optional.

But as PHP functions, macros don't have access to the current template variables.

Tip

You can pass the whole context as an argument by using the special _context variable.

Macros can be defined in any template, and need to be "imported" before being used (see the Import section for more information):

{% import "forms.html" as forms %}

The above import call imports the "forms.html" file (which can contain only macros, or a template and some macros), and import the functions as items of the forms variable.

The macro can then be called at will:

<p>{{ forms.input('username') }}</p>
<p>{{ forms.input('password', none, 'password') }}</p>

If macros are defined and used in the same template, you can use the special _self variable, without importing them:

<p>{{ _self.input('username') }}</p>

When you want to use a macro in another one from the same file, use the _self variable:

{% macro input(name, value, type, size) %}
  <input type="{{ type|default('text') }}" name="{{ name }}" value="{{ value|e }}" size="{{ size|default(20) }}" />
{% endmacro %}

{% macro wrapped_input(name, value, type, size) %}
    <div class="field">
        {{ _self.input(name, value, type, size) }}
    </div>
{% endmacro %}

When the macro is defined in another file, you need to import it:

{# forms.html #}

{% macro input(name, value, type, size) %}
  <input type="{{ type|default('text') }}" name="{{ name }}" value="{{ value|e }}" size="{{ size|default(20) }}" />
{% endmacro %}

{# shortcuts.html #}

{% macro wrapped_input(name, value, type, size) %}
    {% import "forms.html" as forms %}
    <div class="field">
        {{ forms.input(name, value, type, size) }}
    </div>
{% endmacro %}

Filters

Filter sections allow you to apply regular Twig filters on a block of template data. Just wrap the code in the special filter section:

{% filter upper %}
  This text becomes uppercase
{% endfilter %}

You can also chain filters:

{% filter lower|escape %}
  <strong>SOME TEXT</strong>
{% endfilter %}

It should return &lt;strong&gt;some text&lt;/strong&gt;.

Assignments

Inside code blocks you can also assign values to variables. Assignments use the set tag and can have multiple targets:

{% set foo = 'foo' %}

{% set foo = [1, 2] %}

{% set foo = {'foo': 'bar'} %}

{% set foo = 'foo' ~ 'bar' %}

{% set foo, bar = 'foo', 'bar' %}

The set tag can also be used to 'capture' chunks of text:

{% set foo %}
  <div id="pagination">
    ...
  </div>
{% endset %}

Caution!

If you enable automatic output escaping, Twig will only consider the content to be safe when capturing chunks of text.

Extends

The extends tag can be used to extend a template from another one. You can have multiple of them in a file but only one of them may be executed at the time. There is no support for multiple inheritance. See the section about Template inheritance above for more information.

Block

Blocks are used for inheritance and act as placeholders and replacements at the same time. They are documented in detail as part of the section about Template inheritance above.

Include

The include statement is useful to include a template and return the rendered content of that file into the current namespace:

{% include 'header.html' %}
  Body
{% include 'footer.html' %}

Included templates have access to the variables of the active context.

You can add additional variables by passing them after the with keyword:

{# the foo template will have access to the variables from the current context and the foo one #}
{% include 'foo' with {'foo': 'bar'} %}

{% set vars = {'foo': 'bar'} %}
{% include 'foo' with vars %}

You can disable access to the context by appending the only keyword:

{# only the foo variable will be accessible #}
{% include 'foo' with {'foo': 'bar'} only %}
{# no variable will be accessible #}
{% include 'foo' only %}

Tip

When including a template created by an end user, you should consider sandboxing it. More information in the "Twig for Developers" chapter.

The template name can be any valid Twig expression:

{% include some_var %}
{% include ajax ? 'ajax.html' : 'not_ajax.html' %}

And if the expression evaluates to a Twig_Template object, Twig will use it directly:

// {% include template %}

$template = $twig->loadTemplate('some_template.twig');

$twig->loadTemplate('template.twig')->display(array('template' => $template));

Import

Twig supports putting often used code into macros. These macros can go into different templates and get imported from there.

There are two ways to import templates. You can import the complete template into a variable or request specific macros from it.

Imagine we have a helper module that renders forms (called forms.html):

{% macro input(name, value, type, size) %}
    <input type="{{ type|default('text') }}" name="{{ name }}" value="{{ value|e }}" size="{{ size|default(20) }}" />
{% endmacro %}

{% macro textarea(name, value, rows) %}
    <textarea name="{{ name }}" rows="{{ rows|default(10) }}" cols="{{ cols|default(40) }}">{{ value|e }}</textarea>
{% endmacro %}

The easiest and most flexible is importing the whole module into a variable. That way you can access the attributes:

{% import 'forms.html' as forms %}

<dl>
    <dt>Username</dt>
    <dd>{{ forms.input('username') }}</dd>
    <dt>Password</dt>
    <dd>{{ forms.input('password', none, 'password') }}</dd>
</dl>
<p>{{ forms.textarea('comment') }}</p>

Alternatively you can import names from the template into the current namespace:

{% from 'forms.html' import input as input_field, textarea %}

<dl>
    <dt>Username</dt>
    <dd>{{ input_field('username') }}</dd>
    <dt>Password</dt>
    <dd>{{ input_field('password', type='password') }}</dd>
</dl>
<p>{{ textarea('comment') }}</p>

Importing is not needed if the macros and the template are defined in the same file; use the special _self variable instead:

{# index.html template #}

{% macro textarea(name, value, rows) %}
    <textarea name="{{ name }}" rows="{{ rows|default(10) }}" cols="{{ cols|default(40) }}">{{ value|e }}</textarea>
{% endmacro %}

<p>{{ _self.textarea('comment') }}</p>

But you can still create an alias by importing from the _self variable:

{# index.html template #}

{% macro textarea(name, value, rows) %}
    <textarea name="{{ name }}" rows="{{ rows|default(10) }}" cols="{{ cols|default(40) }}">{{ value|e }}</textarea>
{% endmacro %}

{% import _self as forms %}

<p>{{ forms.textarea('comment') }}</p>

Expressions

Twig allows basic expressions everywhere. These work very similar to regular PHP and even if you're not working with PHP you should feel comfortable with it.

The operator precedence is as follows, with the lowest-precedence operators listed first: or, and, ==, !=, <, >, >=, <=, in, +, -, ~, *, /, %, //, is, .., and **.

Literals

The simplest form of expressions are literals. Literals are representations for PHP types such as strings, numbers, and arrays. The following literals exist:

  • "Hello World": Everything between two double or single quotes is a string. They are useful whenever you need a string in the template (for example as arguments to function calls, filters or just to extend or include a template).
  • 42 / 42.23: Integers and floating point numbers are created by just writing the number down. If a dot is present the number is a float, otherwise an integer.
  • ["foo", "bar"]: Arrays are defined by a sequence of expressions separated by a comma (,) and wrapped with squared brackets ([]).
  • {"foo": "bar"}: Hashes are defined by a list of keys and values separated by a comma (,) and wrapped with curly braces ({}). A value can be any valid expression.
  • true / false: true represents the true value, false represents the false value.
  • none: none represents no specific value (the equivalent of null in PHP). This is the value returned when a variable does not exist.

Arrays and hashes can be nested:

{% set foo = [1, {"foo": "bar"}] %}

Math

Twig allows you to calculate with values. This is rarely useful in templates but exists for completeness' sake. The following operators are supported:

  • +: Adds two objects together (the operands are casted to numbers). {{ 1 + 1 }} is 2.
  • -: Substracts the second number from the first one. {{ 3 - 2 }} is 1.
  • /: Divides two numbers. The return value will be a floating point number. {{ 1 / 2 }} is {{ 0.5 }}.
  • %: Calculates the remainder of an integer division. {{ 11 % 7 }} is 4.
  • //: Divides two numbers and returns the truncated integer result. {{ 20 // 7 }} is 2.
  • *: Multiplies the left operand with the right one. {{ 2 * 2 }} would return 4.
  • **: Raises the left operand to the power of the right operand. {{ 2**3 }} would return 8.

Logic

For if statements, for filtering or if expressions it can be useful to combine multiple expressions:

  • and: Returns true if the left and the right operands are both true.
  • or: Returns true if the left or the right operand is true.
  • not: Negates a statement.
  • (expr): Groups an expression.

Comparisons

The following comparison operators are supported in any expression: ==, !=, <, >, >=, and <=.

Containment Operator

The in operator performs containment test.

It returns true if the left operand is contained in the right:

{# returns true #}

{{ 1 in [1, 2, 3] }}

{{ 'cd' in 'abcde' }}

Tip

You can use this filter to perform a containment test on strings, arrays, or objects implementing the Traversable interface.

To perform a negative test, use the not in operator:

{% if 1 not in [1, 2, 3] %}

{# is equivalent to #}
{% if not (1 in [1, 2, 3]) %}

Tests

The is operator performs tests. Tests can be used to test a variable against a common expression. The right operand is name of the test:

{# find out if a variable is odd #}

{{ name is odd }}

Tests can accept arguments too:

{% if loop.index is divisibleby(3) %}

Tests can be negated by using the not in operator:

{% if loop.index is not divisibleby(3) %}

{# is equivalent to #}
{% if not (loop.index is divisibleby(3)) %}

The built-in tests section below describes all the built-in tests.

Other Operators

The following operators are very useful but don't fit into any of the other two categories:

  • ..: Creates a sequence based on the operand before and after the operator (see the for tag for some usage examples).

  • |: Applies a filter.

  • ~: Converts all operands into strings and concatenates them. {{ "Hello " ~ name ~ "!" }} would return (assuming name is 'John') Hello John!.

  • ., []: Gets an attribute of an object.

  • ?:: Twig supports the PHP ternary operator:

    {{ foo ? 'yes' : 'no' }}
    

List of built-in Filters

date

The date filter is able to format a date to a given format:

{{ post.published_at|date("m/d/Y") }}

The date filter accepts any date format supported by DateTime and DateTime instances. For instance, to display the current date, filter the word "now":

{{ "now"|date("m/d/Y") }}

format

The format filter formats a given string by replacing the placeholders (placeholders follows the printf notation):

{{ "I like %s and %s."|format(foo, "bar") }}

{# returns I like foo and bar. (if the foo parameter equals to the foo string) #}

replace

The replace filter formats a given string by replacing the placeholders (placeholders are free-form):

{{ "I like %this% and %that%."|replace({'%this%': foo, '%that%': "bar"}) }}

{# returns I like foo and bar. (if the foo parameter equals to the foo string) #}

url_encode

The url_encode filter URL encodes a given string.

json_encode

The json_encode filter returns the JSON representation of a string.

title

The title filter returns a titlecased version of the value. I.e. words will start with uppercase letters, all remaining characters are lowercase.

capitalize

The capitalize filter capitalizes a value. The first character will be uppercase, all others lowercase.

upper

The upper filter converts a value to uppercase.

lower

The lower filter converts a value to lowercase.

striptags

The striptags filter strips SGML/XML tags and replace adjacent whitespace by one space.

join

The join filter returns a string which is the concatenation of the strings in the sequence. The separator between elements is an empty string per default, you can define it with the optional parameter:

{{ [1, 2, 3]|join('|') }}
{# returns 1|2|3 #}

{{ [1, 2, 3]|join }}
{# returns 123 #}

reverse

The reverse filter reverses an array or an object if it implements the Iterator interface.

length

The length filters returns the number of items of a sequence or mapping, or the length of a string.

sort

The sort filter sorts an array.

default

The default filter returns the passed default value if the value is undefined or empty, otherwise the value of the variable:

{{ var|default('var is not defined') }}

{{ var.foo|default('foo item on var is not defined') }}

{{ ''|default('passed var is empty')  }}

Note

Read the documentation for the defined and empty tests below to learn more about their semantics.

keys

The keys filter returns the keys of an array. It is useful when you want to iterate over the keys of an array:

{% for key in array|keys %}
    ...
{% endfor %}

escape, e

The escape filter converts the characters &, <, >, ', and " in strings to HTML-safe sequences. Use this if you need to display text that might contain such characters in HTML.

Note

Internally, escape uses the PHP htmlspecialchars function.

raw

The raw filter marks the value as safe which means that in an environment with automatic escaping enabled this variable will not be escaped if raw is the last filter applied to it.

{% autoescape true }
  {{ var|raw }} {# var won't be escaped #}
{% endautoescape %}

merge

The merge filter merges an array or a hash with the value:

{% set items = { 'apple': 'fruit', 'orange': 'fruit' } %}

{% set items = items|merge({ 'peugeot': 'car' }) %}

{# items now contains { 'apple': 'fruit', 'orange': 'fruit', 'peugeot': 'car' } #}

List of built-in Tests

divisibleby

divisibleby checks if a variable is divisible by a number:

{% if loop.index is divisibleby(3) %}

none

none returns true if the variable is none:

{{ var is none }}

even

even returns true if the given number is even:

{{ var is even }}

odd

odd returns true if the given number is odd:

{{ var is odd }}

sameas

sameas checks if a variable points to the same memory address than another variable:

{% if foo.attribute is sameas(false) %}
    the foo attribute really is the ``false`` PHP value
{% endif %}

constant

constant checks if a variable has the exact same value as a constant. You can use either global constants or class constants:

{% if post.status is constant('Post::PUBLISHED') %}
    the status attribute is exactly the same as Post::PUBLISHED
{% endif %}

defined

defined checks if a variable is defined in the current context. This is very useful if you use the strict_variables option:

{# defined works with variable names #}
{% if foo is defined %}
    ...
{% endif %}

{# and attributes on variables names #}
{% if foo.bar is defined %}
    ...
{% endif %}

empty

empty checks if a variable is empty:

{# evaluates to true if the foo variable is null, false, or the empty string #}
{% if foo is empty %}
    ...
{% endif %}

List of Global Functions

The following functions are available in the global scope by default:

range

Returns a list containing an arithmetic progression of integers. When step is given, it specifies the increment (or decrement):

{% for i in range(0, 3) %}
    {{ i }},
{% endfor %}

{# returns 0, 1, 2, 3 #}

{% for i in range(0, 6, 2) %}
    {{ i }},
{% endfor %}

{# returns 0, 2, 4, 6 #}

Tip

The range function works as the native PHP range function.

The .. operator is a syntactic sugar for the range function (with a step of 1):

{% for i in 0..10 %}
    {{ i }},
{% endfor %}

cycle

The cycle function can be used to cycle on an array of values:

{% for i in 0..10 %}
    {{ cycle(['odd', 'even'], i) }}
{% endfor %}

The array can contain any number of values:

{% set fruits = ['apple', 'orange', 'citrus'] %}

{% for i in 0..10 %}
    {{ cycle(fruits, i) }}
{% endfor %}

constant

constant returns the constant value for a given string:

{{ some_date|date(constant('DATE_W3C')) }}

Extensions

Twig can be easily extended. If you are looking for new tags or filters, have a look at the Twig official extension repository: http://github.com/fabpot/Twig-extensions.

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