How to dynamically add field to a form with Python Django?

To dynamically add field to a form with Python Django, we can add the form with a for loop.

For instance, we write

class MyForm(forms.Form):
    original_field = forms.CharField()
    extra_field_count = forms.CharField(widget=forms.HiddenInput())

    def __init__(self, *args, **kwargs):
        extra_fields = kwargs.pop('extra', 0)

        super(MyForm, self).__init__(*args, **kwargs)
        self.fields['extra_field_count'].initial = extra_fields

        for index in range(int(extra_fields)):
            self.fields['extra_field_{index}'.format(index=index)] = \
                forms.CharField()

to create the MyForm form that has a for loop in the __init__ method that creates CharFields and add them into the self.fields dictionary dynamically.

Then in our view, we can use the form with

def myview(request):
    if request.method == 'POST':
        form = MyForm(request.POST, extra=request.POST.get('extra_field_count'))
        if form.is_valid():
            print "valid!"
    else:
        form = MyForm()
    return render(request, "template", { 'form': form })

We set the extra argument to a list we get from request.POST.get.

Then we render the template for the view with

<form>
    <div id="forms">
        {{ form.as_p }}
    </div>
    <button id="add-another">add another</button>
    <input type="submit" />
</form>