[FIXED] Add class to form field Django ModelForm

Issue

I am trying to write a Bootstrap Form with Django ModelForm. I have read the Django Documentation Django Documentation about Forms, so I have this code:

<div class="form-group">
{{ form.subject.errors }}
<label for="{{ form.subject.id_for_label }}">Email subject:</label>
{{ form.subject }}</div>

The {{form.subject}} is rendered by Django, for example in CharField field model, as input tag,

<input type="text"....> etc.

I need add "form-control" class to every input in order to get Bootstrap input appearance (without third-party packages). I found this solution Django add class to form <input ..> field. Is there any way to add a class to every field by default without specifying it in every attribute of the class of Form class?

class ExampleForm(forms.Form):
   name = forms.CharField(widget=forms.TextInput(attrs={'class':'form-control'}))
   email = forms.CharField(widget=forms.TextInput(attrs={'class':'form-control'}))
   address = forms.CharField(widget=forms.TextInput(attrs={'class':'form-control'}))
   country = forms.CharField(widget=forms.TextInput(attrs={'class':'form-control'}))

and so on ..

Solution

If you can't use a third-party app and want to add a class (e.g., "form-control") to every field in a form in a DRY manner, you can do so in the form class __init__() method like so:

class ExampleForm(forms.Form):
    # Your declared form fields here
    ...

    def __init__(self, *args, **kwargs):
        super(ExampleForm, self).__init__(*args, **kwargs)
        for visible in self.visible_fields():
            visible.field.widget.attrs['class'] = 'form-control'

You might need to handle checking for existing classes in attrs too, if for some reason you'll be adding classes both declaratively and within __init__(). The above code doesn't account for that case.

Worth mentioning:

You specified that you don't want to use third-party packages. However, I'll take one second to mention that one of the simplest ways of automatically making forms render in the style of Bootstrap is to use django-crispy-forms, like this:

# settings.py
CRISPY_TEMPLATE_PACK = 'bootstrap3'

# forms.py
from crispy_forms.helper import FormHelper
class ExampleForm(forms.Form):
    # Your declared form fields here
    ...
    helper = FormHelper()

# In your template, this renders the form Bootstrap-style:
{% load crispy_forms_tags %}
{% crispy form %}

Answered By - Christian Abbott