Six Django template tags not often used in tutorials

This article is for those who don't read the documentation, and I, who had the Dash app for a few months now, which I never tinkered until last night.

During my first day on my internship a couple of months back, I was tasked to work on the scaffold of the company on which I was overwhelmed with the tags on it and never really bothered to research them.

Some of these are taken from the scaffold, some not.

Side note: There are spaces on the template tag because I have not figured out how to make the tags work on this site.

1.) for...empty

The for tag can take an optional {% empty %} clause whose text is displayed if the given array is empty or could not be found:

{% for student in student_list %}
    ...
{% empty %}
    ...
{% endfor %}

Which is also equivalent to:


  {% if student_list %}
    {% for student in student_list %}
      ...
    { % endfor %}
  {% else %}
    ...
  {% endif %}

2.) lorem

No, you don't need any other packages nor copy/paste a lorem text. This tag displays random “lorem ipsum” Latin text. This is useful for providing sample data in templates. Unless, of course, you don't.

{%  lorem [count] [method] [random] %}

e.g.

- {% lorem %} # will output the common “lorem ipsum” paragraph.
- {% lorem 3 p %} # will output the common “lorem ipsum” paragraph and two random paragraphs each wrapped in HTML <p> tags.
- {% lorem 2 w random %} # will output two random Latin words.

3.) now

Displays the current date and/or time, using a format according to the given string. Such string can contain format specifiers characters as described in the date filter section.

{% now "jS F Y" %}

4.) resetcycle

Resets a previous cycle so that it restarts from its first item at its next encounter. Without arguments, {% resetcycle %} will reset the last {% cycle %} defined in the template.

{% for coach in coach_list %}
      {{ coach.name }}
    {% for athlete in coach.athlete_set.all %}
        <p class="{% cycle 'odd' 'even' %}">{{ athlete.name }}</p>
    {% endfor %}
    {% resetcycle %}
{% endfor %}

This example would return this HTML:

<h1>José Mourinho</h1>
<p class="odd">Thibaut Courtois</p>
<p class="even">John Terry</p>
<p class="odd">Eden Hazard</p>

<h1>Carlo Ancelotti</h1>
<p class="odd">Manuel Neuer</p>
<p class="even">Thomas Müller</p>

5.) verbatim

Stops the template engine from rendering the contents of this block tag.
A common use is to allow a JavaScript template layer that collides with Django’s syntax. For example:

{% verbatim %}
    {{if dying}}Still alive.{{/if}}
{% endverbatim %}

You can also designate a specific closing tag, allowing the use of {% endverbatim %} as part of the unrendered contents:

{% verbatim myblock %}
    Avoid template rendering via the {% verbatim %}{% endverbatim %} block.
{% endverbatim myblock %}

6.) widthratio

For creating bar charts and such, this tag calculates the ratio of a given value to a maximum value, and then applies that ratio to a constant.

<img src="#" alt="Imagine an image here"
     height="10" width="{% widthratio this_value max_value max_width %}" />

If this_value is 175, max_value is 200, and max_width is 100, the image in the above example will be 88 pixels wide (because 175/200 = .875; .875 * 100 = 87.5 which is rounded up to 88).
In some cases, you might want to capture the result of the width ratio in a variable. It can be useful, for instance, in a blocktrans like this:

{% widthratio this_value max_value max_width as width %}
{% blocktrans %}The width is: {{ width }}{% endblocktrans %}

Final side note: There are spaces on the template tag because I have not figured out how to make the tags work on this site.

Vicente Reyes