Form wizard¶

How it works¶

Here’s the basic workflow for how a user would use a wizard:

1. The user visits the first page of the wizard, fills in the form and submits it.
2. The server validates the data. If it’s invalid, the form is displayed again, with error messages. If it’s valid, the server saves the current state of the wizard in the backend and redirects to the next step.
3. Step 1 and 2 repeat, for every subsequent form in the wizard.
4. Once the user has submitted all the forms and all the data has been validated, the wizard processes the data – saving it to the database, sending an email, or whatever the application needs to do.

Usage¶

This application handles as much machinery for you as possible. Generally, you just have to do these things:

1. Define a number of Form classes – one per wizard page.
2. Create a WizardView subclass that specifies what to do once all of your forms have been submitted and validated. This also lets you override some of the wizard’s behavior.
3. Create some templates that render the forms. You can define a single, generic template to handle every one of the forms, or you can define a specific template for each form.
4. Add django.contrib.formtools to your INSTALLED_APPS list in your settings file.
5. Point your URLconf at your WizardView as_view() method.

from django import forms

class ContactForm1(forms.Form):
    subject = forms.CharField(max_length=100)
    sender = forms.EmailField()

class ContactForm2(forms.Form):
    message = forms.CharField(widget=forms.Textarea)

{% extends "base.html" %}
{% load i18n %}

{% block head %}
{{ wizard.form.media }}
{% endblock %}

{% block content %}
<p>Step {{ wizard.steps.step1 }} of {{ wizard.steps.count }}</p>
<form action="" method="post">{% csrf_token %}
<table>
{{ wizard.management_form }}
{% if wizard.form.forms %}
    {{ wizard.form.management_form }}
    {% for form in wizard.form.forms %}
        {{ form }}
    {% endfor %}
{% else %}
    {{ wizard.form }}
{% endif %}
</table>
{% if wizard.steps.prev %}
<button name="wizard_goto_step" type="submit" value="{{ wizard.steps.first }}">{% trans "first step" %}</button>
<button name="wizard_goto_step" type="submit" value="{{ wizard.steps.prev }}">{% trans "prev step" %}</button>
{% endif %}
<input type="submit" value="{% trans "submit" %}"/>
</form>
{% endblock %}

from django.conf.urls import patterns

from myapp.forms import ContactForm1, ContactForm2
from myapp.views import ContactWizard

urlpatterns = patterns('',
    (r'^contact/$', ContactWizard.as_view([ContactForm1, ContactForm2])),
)

from django.http import HttpResponseRedirect
from django.contrib.formtools.wizard.views import SessionWizardView

FORMS = [("address", myapp.forms.AddressForm),
         ("paytype", myapp.forms.PaymentChoiceForm),
         ("cc", myapp.forms.CreditCardForm),
         ("confirmation", myapp.forms.OrderForm)]

TEMPLATES = {"address": "checkout/billingaddress.html",
             "paytype": "checkout/paymentmethod.html",
             "cc": "checkout/creditcard.html",
             "confirmation": "checkout/confirmation.html"}

def pay_by_credit_card(wizard):
    """Return true if user opts to pay by credit card"""
    # Get cleaned data from payment step
    cleaned_data = wizard.get_cleaned_data_for_step('paytype') or {'method': 'none'}
    # Return true if the user selected credit card
    return cleaned_data['method'] == 'cc'


class OrderWizard(SessionWizardView):
    def get_template_names(self):
        return [TEMPLATES[self.steps.current]]

    def done(self, form_list, **kwargs):
        do_something_with_the_form_data(form_list)
        return HttpResponseRedirect('/page-to-redirect-to-when-done/')
        ...

urlpatterns = patterns('',
    (r'^checkout/$', OrderWizard.as_view(FORMS, condition_dict={'cc': pay_by_credit_card})),
)

Advanced WizardView methods¶

class WizardView¶

Aside from the done() method, WizardView offers a few advanced method hooks that let you customize how your wizard works.

Some of these methods take an argument step, which is a zero-based counter as string representing the current step of the wizard. (E.g., the first form is '0' and the second form is '1')

WizardView.get_form_prefix(step=None, form=None)¶

Returns the prefix which will be used when calling the form for the given step. step contains the step name, form the form class which will be called with the returned prefix.

If no step is given, it will be determined automatically. By default, this simply uses the step itself and the form parameter is not used.

For more, see the form prefix documentation.

WizardView.get_form_initial(step)¶

Returns a dictionary which will be passed as the initial argument when instantiating the Form instance for step step. If no initial data was provided while initializing the form wizard, an empty dictionary should be returned.

The default implementation:

def get_form_initial(self, step):
    return self.initial_dict.get(step, {})

WizardView.get_form_kwargs(step)¶

Returns a dictionary which will be used as the keyword arguments when instantiating the form instance on given step.

The default implementation:

def get_form_kwargs(self, step):
    return {}

WizardView.get_form_instance(step)¶

This method will be called only if a ModelForm is used as the form for step step.

Returns an Model object which will be passed as the instance argument when instantiating the ModelForm for step step. If no instance object was provided while initializing the form wizard, None will be returned.

The default implementation:

def get_form_instance(self, step):
    return self.instance_dict.get(step, None)

WizardView.get_context_data(form, **kwargs)¶

Returns the template context for a step. You can overwrite this method to add more data for all or some steps. This method returns a dictionary containing the rendered form step.

The default template context variables are:

• Any extra data the storage backend has stored
• form – form instance of the current step
• wizard – the wizard instance itself

Example to add extra variables for a specific step:

def get_context_data(self, form, **kwargs):
    context = super(MyWizard, self).get_context_data(form=form, **kwargs)
    if self.steps.current == 'my_step_name':
        context.update({'another_var': True})
    return context

WizardView.get_prefix(*args, **kwargs)¶

This method returns a prefix for use by the storage backends. Backends use the prefix as a mechanism to allow data to be stored separately for each wizard. This allows wizards to store their data in a single backend without overwriting each other.

You can change this method to make the wizard data prefix more unique to, e.g. have multiple instances of one wizard in one session.

Default implementation:

def get_prefix(self, *args, **kwargs):
    # use the lowercase underscore version of the class name
    return normalize_name(self.__class__.__name__)

WizardView.get_form(step=None, data=None, files=None)¶

This method constructs the form for a given step. If no step is defined, the current step will be determined automatically. The method gets three arguments:

• step – The step for which the form instance should be generated.
• data – Gets passed to the form’s data argument
• files – Gets passed to the form’s files argument

You can override this method to add extra arguments to the form instance.

Example code to add a user attribute to the form on step 2:

def get_form(self, step=None, data=None, files=None):
    form = super(MyWizard, self).get_form(step, data, files)
    if step == '1':
        form.user = self.request.user
    return form

WizardView.process_step(form)¶

Hook for modifying the wizard’s internal state, given a fully validated Form object. The Form is guaranteed to have clean, valid data.

This method gives you a way to post-process the form data before the data gets stored within the storage backend. By default it just returns the form.data dictionary. You should not manipulate the data here but you can use it to do some extra work if needed (e.g. set storage extra data).

Note that this method is called every time a page is rendered for all submitted steps.

The default implementation:

def process_step(self, form):
    return self.get_form_step_data(form)

WizardView.process_step_files(form)¶

This method gives you a way to post-process the form files before the files gets stored within the storage backend. By default it just returns the form.files dictionary. You should not manipulate the data here but you can use it to do some extra work if needed (e.g. set storage extra data).

Default implementation:

def process_step_files(self, form):
    return self.get_form_step_files(form)

WizardView.render_revalidation_failure(step, form, **kwargs)¶

When the wizard thinks all steps have passed it revalidates all forms with the data from the backend storage.

If any of the forms don’t validate correctly, this method gets called. This method expects two arguments, step and form.

The default implementation resets the current step to the first failing form and redirects the user to the invalid form.

Default implementation:

def render_revalidation_failure(self, step, form, **kwargs):
    self.storage.current_step = step
    return self.render(form, **kwargs)

WizardView.get_form_step_data(form)¶

This method fetches the data from the form Form instance and returns the dictionary. You can use this method to manipulate the values before the data gets stored in the storage backend.

Default implementation:

def get_form_step_data(self, form):
    return form.data

WizardView.get_form_step_files(form)¶

This method returns the form files. You can use this method to manipulate the files before the data gets stored in the storage backend.

Default implementation:

def get_form_step_files(self, form):
    return form.files

WizardView.render(form, **kwargs)¶

This method gets called after the GET or POST request has been handled. You can hook in this method to, e.g. change the type of HTTP response.

Default implementation:

def render(self, form=None, **kwargs):
    form = form or self.get_form()
    context = self.get_context_data(form=form, **kwargs)
    return self.render_to_response(context)

WizardView.get_cleaned_data_for_step(step)¶

This method returns the cleaned data for a given step. Before returning the cleaned data, the stored values are revalidated through the form. If the data doesn’t validate, None will be returned.

WizardView.get_all_cleaned_data()¶

This method returns a merged dictionary of all form steps’ cleaned_data dictionaries. If a step contains a FormSet, the key will be prefixed with formset- and contain a list of the formset’s cleaned_data dictionaries. Note that if two or more steps have a field with the same name, the value for that field from the latest step will overwrite the value from any earlier steps.

Providing initial data for the forms¶

WizardView.initial_dict¶

Initial data for a wizard’s Form objects can be provided using the optional initial_dict keyword argument. This argument should be a dictionary mapping the steps to dictionaries containing the initial data for each step. The dictionary of initial data will be passed along to the constructor of the step’s Form:

>>> from myapp.forms import ContactForm1, ContactForm2
>>> from myapp.views import ContactWizard
>>> initial = {
...     '0': {'subject': 'Hello', 'sender': 'user@example.com'},
...     '1': {'message': 'Hi there!'}
... }
>>> # This example is illustrative only and isn't meant to be run in
>>> # the shell since it requires an HttpRequest to pass to the view.
>>> wiz = ContactWizard.as_view([ContactForm1, ContactForm2], initial_dict=initial)(request)
>>> form1 = wiz.get_form('0')
>>> form2 = wiz.get_form('1')
>>> form1.initial
{'sender': 'user@example.com', 'subject': 'Hello'}
>>> form2.initial
{'message': 'Hi there!'}

The initial_dict can also take a list of dictionaries for a specific step if the step is a FormSet.

Handling files¶

WizardView.file_storage¶

To handle FileField within any step form of the wizard, you have to add a file_storage to your WizardView subclass.

This storage will temporarily store the uploaded files for the wizard. The file_storage attribute should be a Storage subclass.

Django provides a built-in storage class (see the built-in filesystem storage class):

from django.conf import settings
from django.core.files.storage import FileSystemStorage

class CustomWizardView(WizardView):
    ...
    file_storage = FileSystemStorage(location=os.path.join(settings.MEDIA_ROOT, 'photos'))

Conditionally view/skip specific steps¶

WizardView.condition_dict¶

The as_view() method accepts a condition_dict argument. You can pass a dictionary of boolean values or callables. The key should match the steps names (e.g. ‘0’, ‘1’).

If the value of a specific step is callable it will be called with the WizardView instance as the only argument. If the return value is true, the step’s form will be used.

This example provides a contact form including a condition. The condition is used to show a message form only if a checkbox in the first step was checked.

The steps are defined in a forms.py file:

from django import forms

class ContactForm1(forms.Form):
    subject = forms.CharField(max_length=100)
    sender = forms.EmailField()
    leave_message = forms.BooleanField(required=False)

class ContactForm2(forms.Form):
    message = forms.CharField(widget=forms.Textarea)

We define our wizard in a views.py:

from django.shortcuts import render_to_response
from django.contrib.formtools.wizard.views import SessionWizardView

def show_message_form_condition(wizard):
    # try to get the cleaned data of step 1
    cleaned_data = wizard.get_cleaned_data_for_step('0') or {}
    # check if the field ``leave_message`` was checked.
    return cleaned_data.get('leave_message', True)

class ContactWizard(SessionWizardView):

    def done(self, form_list, **kwargs):
        return render_to_response('done.html', {
            'form_data': [form.cleaned_data for form in form_list],
        })

We need to add the ContactWizard to our urls.py file:

from django.conf.urls import patterns

from myapp.forms import ContactForm1, ContactForm2
from myapp.views import ContactWizard, show_message_form_condition

contact_forms = [ContactForm1, ContactForm2]

urlpatterns = patterns('',
    (r'^contact/$', ContactWizard.as_view(contact_forms,
        condition_dict={'1': show_message_form_condition}
    )),
)

As you can see, we defined a show_message_form_condition next to our WizardView subclass and added a condition_dict argument to the as_view() method. The key refers to the second wizard step (because of the zero based step index).

How to work with ModelForm and ModelFormSet¶

WizardView.instance_dict¶

WizardView supports ModelForms and ModelFormSets. Additionally to initial_dict, the as_view() method takes an instance_dict argument that should contain model instances for steps based on ModelForm and querysets for steps based on ModelFormSet.

Usage of NamedUrlWizardView¶

class NamedUrlWizardView¶

class NamedUrlSessionWizardView¶

class NamedUrlCookieWizardView¶

There is a WizardView subclass which adds named-urls support to the wizard. By doing this, you can have single urls for every step. You can also use the NamedUrlSessionWizardView or NamedUrlCookieWizardView classes which preselect the backend used for storing information (server-side sessions and browser cookies respectively).

To use the named urls, you have to change the urls.py.

Below you will see an example of a contact wizard with two steps, step 1 with “contactdata” as its name and step 2 with “leavemessage” as its name.

Additionally you have to pass two more arguments to the as_view() method:

• url_name – the name of the url (as provided in the urls.py)
• done_step_name – the name in the url for the done step

Example code for the changed urls.py file:

from django.conf.urls import url, patterns

from myapp.forms import ContactForm1, ContactForm2
from myapp.views import ContactWizard

named_contact_forms = (
    ('contactdata', ContactForm1),
    ('leavemessage', ContactForm2),
)

contact_wizard = ContactWizard.as_view(named_contact_forms,
    url_name='contact_step', done_step_name='finished')

urlpatterns = patterns('',
    url(r'^contact/(?P<step>.+)/$', contact_wizard, name='contact_step'),
    url(r'^contact/$', contact_wizard, name='contact'),
)

Advanced NamedUrlWizardView methods¶

NamedUrlWizardView.get_step_url(step)¶

This method returns the URL for a specific step.

Default implementation:

def get_step_url(self, step):
    return reverse(self.url_name, kwargs={'step': step})