Built-in template tags--> cycle

cycle
Changed in Django 1.0: Cycle among the given strings or variables each time this tag is encountered.

Within a loop, cycles among the given strings each time through the loop:

{% for o in some_list %}
    <tr class="{% cycle 'row1' 'row2' %}">
        ...
    </tr>
{% endfor %}

You can use variables, too. For example, if you have two template variables, rowvalue1 and rowvalue2, you can cycle between their values like this:

{% for o in some_list %}
    <tr class="{% cycle rowvalue1 rowvalue2 %}">
        ...
    </tr>
{% endfor %}

Yes, you can mix variables and strings:

{% for o in some_list %}
    <tr class="{% cycle 'row1' rowvalue2 'row3' %}">
        ...
    </tr>
{% endfor %}

In some cases you might want to refer to the next value of a cycle from outside of a loop. To do this, just give the {% cycle %} tag a name, using "as", like this:

{% cycle 'row1' 'row2' as rowcolors %}

From then on, you can insert the current value of the cycle wherever you'd like in your template:

<tr class="{% cycle rowcolors %}">...</tr>
<tr class="{% cycle rowcolors %}">...</tr>

You can use any number of values in a {% cycle %} tag, separated by spaces. Values enclosed in single (') or double quotes (") are treated as string literals, while values without quotes are treated as template variables.

Note that the variables included in the cycle will not be escaped. This is because template tags do not escape their content. If you want to escape the variables in the cycle, you must do so explicitly:

{% filter force_escape %}
    {% cycle var1 var2 var3 %}
{% endfilter %}

For backwards compatibility, the {% cycle %} tag supports the much inferior old syntax from previous Django versions. You shouldn't use this in any new projects, but for the sake of the people who are still using it, here's what it looks like:

{% cycle row1,row2,row3 %}

In this syntax, each value gets interpreted as a literal string, and there's no way to specify variable values. Or literal commas. Or spaces. Did we mention you shouldn't use this syntax in any new projects?