Django: How to check if field widget is checkbox in the template?

Question

I've created a custom template for rendering form fields:

<tr class="{{field.field.widget.attrs.class}}">
    <th class="label">
        <label for="{{field.auto_id}}">
            {{field.label}}
            {% if not field.field.required %}<span class="optional">(optional)</span>{% endif %}
        </label>
    </th>
    <td class="field">
        {{field}}
        {% if field.errors %}<label class="error" for="{{field.auto_id}}">{{field.errors.0}}</label>{% endif %}
        {% if field.help_text %}<small class="help-text">{{field.help_text}}</small>{% endif %}
    </td>
</tr>

But I want to check if the widget is a checkbox, and if so, render it differently. How can I do that in the template?

Hi - is there a particular reason why you need to do it in the template, rather than setting a custom widget in the form class? — Steve Jalim
– Steve Jalim, Commented Oct 13, 2010 at 19:03
@stevejalim: I can create a custom widget, but it doesn't solve the issue. I want to set colspan=2 and have the label on the right side. This is an issue with how the table row is laid out, not with how the widget is rendered. — mpen
– mpen, Commented Oct 13, 2010 at 19:05
gotcha. One (hacky) way to do it is to pass in a list of fields known to be checkboxes and each time you render the field, check if it's name is in that list, and if so, set your colspan there. Icky, though ;o) — Steve Jalim
– Steve Jalim, Commented Oct 13, 2010 at 20:00
Very icky. I'm trying to clean up all that ick right now, not add more to it :) — mpen
– mpen, Commented Oct 13, 2010 at 20:10

aj3sh · Accepted Answer · 2020-08-14 08:04:32Z

20

Use a custom template filter!

In yourapp/templatetags/my_custom_tags.py:

from django import template
from django.forms import CheckboxInput

register = template.Library()

@register.filter(name='is_checkbox')
def is_checkbox(field):
  return field.field.widget.__class__.__name__ == CheckboxInput().__class__.__name__

In your template:

{% load my_custom_tags %}
 
{% if field|is_checkbox %}
  do something
{% endif %}

Side note on implementation: when I don't instantiate a CheckboxInput, the class name is MediaDefiningClass.

>>> form django.forms import CheckboxInput
KeyboardInterrupt
>>> CheckboxInput.__class__.__name__
'MediaDefiningClass'

edited Aug 14, 2020 at 8:04

aj3sh

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answered Jan 12, 2013 at 9:18

davidtingsu

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2 Comments

rudyryk Over a year ago

And today there's a special Django utility application which has similar checker and other stuff: pypi.python.org/pypi/django-form-utils#is-checkbox

Thibault J Over a year ago

I'd say that it's cleaner to use something like this: return isinstance(field.field.widget, CheckboxInput).

mpen · Accepted Answer · 2010-10-14 03:40:26Z

12

{{ field.field.widget.input_type }} will get you this info for a lot of widgets, but not all. I'm not sure if it'll work for the default checkbox widget or not. Worth a shot.

edited Oct 14, 2010 at 3:40

mpen

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answered Oct 14, 2010 at 1:45

Jeff Croft

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1 Comment

mpen Over a year ago

Don't think CheckboxInput has this attribute... it does however appear to have a check_test attribute... I don't know if it's unique to the checkbox input...but it's working for now... bit of a hack though.

Alexandre · Accepted Answer · 2013-01-28 20:30:03Z

7

It is kind of late to answer, but I implemented something similar to what is done in Django's admin.

First, I added a new attribute is_checkbox to the Field class:

# forms.py
from django import forms
from django.forms.fields import Field
setattr(Field, 'is_checkbox', lambda self: isinstance(self.widget, forms.CheckboxInput ))

Then, I can easily detect a CheckboxInput widget in the template. Here is an example to render checkboxes to the left and other widgets to the right:

{% if field.field.is_checkbox %}
    {{ field }} {{ field.label_tag }}
{% else %}
    {{ field.label }} {{ field }}
{% endif %}

answered Jan 28, 2013 at 20:30

Alexandre

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