A django iconbool filter

Published on Aug. 26, 2015, 11:58 a.m.

django filter python

Django's template laguage includes a lot of really useful built-in tags and filters, but sometimes you just need to build your own. There are many reasons why you might want to do this, but I'm lazy, and I like to build filters and tags that let me take shortcuts in the template.

Here's one example of a simple filter that let's me be lazy: an iconbool filter.

Motivation

I really like Font-Awesome, and any time I need to represent a boolean value, I like to use an icon. Here's one such example:

User has Widget?
{% if user.has_widget %}
  <i class="fa fa-check"></i> Yes
{% else %}
  <i class="fa fa-ban"></i> No
{% endif %}

Now, that's not a lot of code, but if you're doing a lot of this type of markup, it can get tedious really quick (imagine building a grid of this kind of content)!

Wouldn't it be so much nicer to write this, instead? (Yes, it would!)

User has Widget? {{ user.has_widget|iconbool }}

Build your custom filter

We can accomplish the above with a simple, custom django filter. Let's call it iconbool. It's going to be a simple function that returns a very simple string of markup based on some input.

from django import template
from django.utils.safestring import mark_safe

register = template.Library()


@register.filter("iconbool", is_safe=True)
def iconbool(value):
    """Given a boolean value, this filter outputs a font-awesome icon + the
    word "Yes" or "No"

    Example Usage:

        {{ user.has_widget|iconbool }}

    """
    if bool(value):
        result = '<i class="fa fa-check"></i> Yes'
    else:
        result = '<i class="fa fa-ban"></i> No'
    return mark_safe(result)

That's it! Put this in your app's templatetags directory (for example: myapp/templatetags/myapp_filters.py), and remember to load the template library in your templates (e.g. {% load myapp_filters %}).

And remember, being lazy is good! Don't forget that django template filters can save you lots of work.

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