Define css class in django Forms

Question

Yet another solution that doesn't require changes in python code and so is better for designers and one-off presentational changes: django-widget-tweaks. Hope somebody will find it useful.

Answered my own question. Sigh

http://docs.djangoproject.com/en/dev/ref/forms/widgets/#django.forms.Widget.attrs

I didn't realize it was passed into the widget constructor.

Here is another solution for adding class definitions to the widgets after declaring the fields in the class.

def __init__(self, *args, **kwargs):
    super(SampleClass, self).__init__(*args, **kwargs)
    self.fields['name'].widget.attrs['class'] = 'my_class'

Use django-widget-tweaks, it is easy to use and works pretty well.

Otherwise this can be done using a custom template filter.

Considering you render your form this way :

<form action="/contact/" method="post">
    {{ form.non_field_errors }}
    <div class="fieldWrapper">
        {{ form.subject.errors }}
        <label for="id_subject">Email subject:</label>
        {{ form.subject }}
    </div>
</form>

form.subject is an instance of BoundField which has the as_widget method.

you can create a custom filter "addcss" in "my_app/templatetags/myfilters.py"

from django import template

register = template.Library()

@register.filter(name='addcss')
def addcss(value, arg):
    css_classes = value.field.widget.attrs.get('class', '').split(' ')
    if css_classes and arg not in css_classes:
        css_classes = '%s %s' % (css_classes, arg)
    return value.as_widget(attrs={'class': css_classes})

And then apply your filter:

{% load myfilters %}
<form action="/contact/" method="post">
    {{ form.non_field_errors }}
    <div class="fieldWrapper">
        {{ form.subject.errors }}
        <label for="id_subject">Email subject:</label>
        {{ form.subject|addcss:'MyClass' }}
    </div>
</form>

form.subjects will then be rendered with the "MyClass" css class.

Hope this help.

EDIT 1

• Update filter according to dimyG's answer

• Add django-widget-tweak link

EDIT 2

• Update filter according to Bhyd's comment