Define css class in django Forms

Question

Assume I have a form

class SampleClass(forms.Form):
    name = forms.CharField(max_length=30)
    age = forms.IntegerField()
    django_hacker = forms.Boolea         


        

Answer 1

In case that you want to add a class to a form's field in a template (not in view.py or form.py) for example in cases that you want to modify 3rd party apps without overriding their views, then a template filter as described in Charlesthk answer is very convenient. But in this answer the template filter overrides any existing classes that the field might has.

I tried to add this as an edit but it was suggested to be written as a new answer.

So, here is a template tag that respects the existing classes of the field:

from django import template

register = template.Library()


@register.filter(name='addclass')
def addclass(field, given_class):
    existing_classes = field.field.widget.attrs.get('class', None)
    if existing_classes:
        if existing_classes.find(given_class) == -1:
            # if the given class doesn't exist in the existing classes
            classes = existing_classes + ' ' + given_class
        else:
            classes = existing_classes
    else:
        classes = given_class
    return field.as_widget(attrs={"class": classes})

Answer 2

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.

Answer 3

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

Answer 4

Expanding on the method pointed to at docs.djangoproject.com:

class MyForm(forms.Form): 
    comment = forms.CharField(
            widget=forms.TextInput(attrs={'size':'40'}))

I thought it was troublesome to have to know the native widget type for every field, and thought it funny to override the default just to put a class name on a form field. This seems to work for me:

class MyForm(forms.Form): 
    #This instantiates the field w/ the default widget
    comment = forms.CharField()

    #We only override the part we care about
    comment.widget.attrs['size'] = '40'

This seems a little cleaner to me.

Answer 5

If you want all the fields in the form to inherit a certain class, you just define a parent class, that inherits from forms.ModelForm, and then inherit from it

class BaseForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super(BaseForm, self).__init__(*args, **kwargs)
        for field_name, field in self.fields.items():
            field.widget.attrs['class'] = 'someClass'


class WhateverForm(BaseForm):
    class Meta:
        model = SomeModel

This helped me to add the 'form-control' class to all of the fields on all of the forms of my application automatically, without adding replication of code.

Answer 6

Simply add the classes to your form as follows.

class UserLoginForm(forms.Form):
    username = forms.CharField(widget=forms.TextInput(
        attrs={
        'class':'form-control',
        'placeholder':'Username'
        }
    ))
    password = forms.CharField(widget=forms.PasswordInput(
        attrs={
        'class':'form-control',
        'placeholder':'Password'
        }
    ))