Django: how to change shortcut using formet extra?

I assume that you want the result of the first form to determine the number of fields and their labels of the second, you can look at Django's form widgets . But here's a simple, non-form-wizard (and perhaps less ideal / maintainable) way to do it, using a formset method __init__

to change form labels *:

forms.py:

# File: forms.py
from django import forms
from django.forms.formsets import BaseFormSet


# What you've called 'GetMachine'
class MachineForm(forms.Form):
    no_of_lines = forms.IntegerField(max_value=4)


# What you've called 'GetLine'
class LineForm(forms.Form):
    beamline_name = forms.CharField(max_length=15, label='Name of Beamline')


# Create a custom formset and override __init__
class BaseLineFormSet(BaseFormSet):
    def __init__(self, *args, **kwargs):
        super(BaseLineFormSet, self).__init__(*args, **kwargs)
        no_of_forms = len(self)
        for i in range(0, no_of_forms):
            self[i].fields['beamline_name'].label += "-%d" % (i + 1)

      

        
        
        
      

    

views.py:

# File: views.py
from django.forms.formsets import formset_factory
from django.shortcuts import render_to_response
from django.template import RequestContext
from django.http import HttpResponseRedirect
from django.core.urlresolvers import reverse
from forms import MachineForm, LineForm, BaseLineFormSet


def get_no_of_lines(request):
    if request.method == 'POST':
        machine_form = MachineForm(request.POST)
        if machine_form.is_valid():
            # At this point, form fields have already been 
            # converted to Python data types :)
            # so no need to convert `line_no` to an integer
            no_of_lines = machine_form.cleaned_data['no_of_lines']
            return HttpResponseRedirect(reverse('line_form', kwargs={'no_of_lines': no_of_lines}))
    else:
        # It looks to me like you probably don't mean to
        # use formsets here (but a form instead)
        machine_form = MachineForm()

    c = RequestContext(request, {
        'machine_form': machine_form,
    })
    return render_to_response('get_no_of_lines.html', c)


def line_form(request, no_of_lines):
    # You probably should validate this number (again).
    # In fact, you probably need to validate first form (MachineForm).
    # ...But I'm assuming it'll be valid in this example.
    no_of_lines = int(no_of_lines)
    LineFormSet = formset_factory(LineForm, extra=no_of_lines, formset=BaseLineFormSet)
    if request.method == "POST":
        formset = LineFormSet(request.POST, request.FILES)
        if formset.is_valid():
            pass
            # Do stuff with form submission
            # Redirect

    else:
        formset = LineFormSet()

    c = RequestContext(request, {
        'formset': formset,
    })
    return render_to_response('line_form.html', c)

      

        
        
        
      

    

urls.py:

from django.conf.urls import url, patterns
from views import get_no_of_lines, line_form


urlpatterns = patterns('',
     url(r'^$', get_no_of_lines, name='get_no_of_lines'),
     url(r'^line_form/(?P<no_of_lines>\d{1})$', line_form, name='line_form'),
)

      

        
        
        
      

    

get_no_of_lines.html:

<form method="POST">
{% csrf_token %}
{{ machine_form }}
</form>

      

        
        
        
      

    

line_form.html:

<form method="POST">
{% csrf_token %}
{{ formset.as_p }}

      

        
        
        
      

    

The reason I say this approach is probably not the best way to do it is because you have to check no_of_lines

against the view line_form

(which could be> 4, so you have to do the check here and inject the validation logic, not have it in one place - the form). And if you need to add a new field to the first form, you will most likely have to change the code. So therefore I would recommend looking into the forms wizard .

• For additional or dynamic shapes, see Jacob Kaplan-Moss's post on creating a dynamic shape .