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Hackernoon logoSix Django Template Tags Not Often Presented in Tutorials by@highcenbug

Six Django Template Tags Not Often Presented in Tutorials

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@highcenbugVicente Reyes

Freelance Developer | I'm looking for work! www.icenreyes.xyz

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 about them.

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

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.

{% npw "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:

{% verabtim %}
   {{ 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 widthratio 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%}

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