Six Django Template Tags Not Often Presented 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  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 %}
        {{ athlete.name }}
    {% endfor %}
    {% resetcycle %}
{% endfor %}

This example would return this HTML:

José Mourinho
Thibaut Courtois
John Terry
Eden Hazard

Carlo Ancelotti
Manuel Neuer
Thomas Müller

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.

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