Add class to form field Django ModelForm

Question

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 ..

Answer 1

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 %}