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>

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 %}

The loop variable

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

{% for user in users %}
    {{ loop.index }} - {{ user.username }}
{% endfor %}

Adding a condition

Unlike in PHP, it's not possible to break or continue in a loop. You can however filter the sequence during iteration which allows you to skip items. The following example skips all the users which are not active:

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

The advantage is that the special loop variable will count correctly thus not counting the users not iterated over. Keep in mind that properties like loop.last will not be defined when using loop conditions.

The else Clause

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>

Iterating over Keys

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>

Iterating over Keys and Values

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>

Iterating over a Subset

You might want to iterate over a subset of values. This can be achieved using the slice filter:

<h1>Top Ten Members</h1>
<ul>
    {% for user in users|slice(0, 10) %}
        <li>{{ user.username|e }}</li>
    {% endfor %}
</ul>