deb-python-django-formtools/docs/wizard.rst

Form wizard

formtools.wizard.views

Django comes with an optional "form wizard" application that splits forms <django.forms> across multiple Web pages. It maintains state in one of the backends so that the full server-side processing can be delayed until the submission of the final form.

You might want to use this if you have a lengthy form that would be too unwieldy for display on a single page. The first page might ask the user for core information, the second page might ask for less important information, etc.

The term "wizard", in this context, is explained on Wikipedia.

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 ~django.forms.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 formtools to your INSTALLED_APPS list in your settings file.
5. Point your URLconf at your WizardView ~WizardView.as_view method.

Defining Form classes

The first step in creating a form wizard is to create the ~django.forms.Form classes. These should be standard django.forms.Form classes, covered in the forms documentation <django.forms>. These classes can live anywhere in your codebase, but convention is to put them in a file called forms.py in your application.

For example, let's write a "contact form" wizard, where the first page's form collects the sender's email address and subject, and the second page collects the message itself. Here's what the forms.py might look like:

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)

Note

In order to use ~django.forms.FileField in any form, see the section Handling files <wizard-files> below to learn more about what to do.

Creating a WizardView subclass

The next step is to create a formtools.wizard.views.WizardView subclass. You can also use the SessionWizardView or CookieWizardView classes which preselect the backend used for storing information during execution of the wizard (as their names indicate, server-side sessions and browser cookies respectively).

Note

To use the SessionWizardView follow the instructions in the sessions documentation <django.contrib.sessions> on how to enable sessions.

We will use the SessionWizardView in all examples but is completely fine to use the CookieWizardView instead. As with your ~django.forms.Form classes, this WizardView class can live anywhere in your codebase, but convention is to put it in views.py.

The only requirement on this subclass is that it implement a ~WizardView.done() method.

WizardView.done(form_list, form_dict, **kwargs)

This method specifies what should happen when the data for every form is submitted and validated. This method is passed a list and dictionary of validated ~django.forms.Form instances.

In this simplistic example, rather than performing any database operation, the method simply renders a template of the validated data:

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

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],
        })

Note that this method will be called via POST, so it really ought to be a good Web citizen and redirect after processing the data. Here's another example:

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

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

In addition to form_list, the ~WizardView.done method is passed a form_dict, which allows you to access the wizard's forms based on their step names. This is especially useful when using NamedUrlWizardView, for example:

def done(self, form_list, form_dict, **kwargs):
    user = form_dict['user'].save()
    credit_card = form_dict['credit_card'].save()
    # ...

1.7

Previously, the form_dict argument wasn't passed to the done method.

See the section Advanced WizardView methods <wizardview-advanced-methods> below to learn about more WizardView hooks.

Creating templates for the forms

Next, you'll need to create a template that renders the wizard's forms. By default, every form uses a template called formtools/wizard/wizard_form.html. You can change this template name by overriding either the ~django.views.generic.base.TemplateResponseMixin.template_name attribute or the ~django.views.generic.base.TemplateResponseMixin.get_template_names() method, which are documented in the ~django.views.generic.base.TemplateResponseMixin documentation. The latter one allows you to use a different template for each form (see the example below <wizard-template-for-each-form>).

This template expects a wizard object that has various items attached to it:

• form -- The ~django.forms.Form or ~django.forms.formsets.BaseFormSet instance for the current step (either empty or with errors).
• steps -- A helper object to access the various steps related data:
  • step0 -- The current step (zero-based).
  • step1 -- The current step (one-based).
  • count -- The total number of steps.
  • first -- The first step.
  • last -- The last step.
  • current -- The current (or first) step.
  • next -- The next step.
  • prev -- The previous step.
  • index -- The index of the current step.
  • all -- A list of all steps of the wizard.

You can supply additional context variables by using the ~WizardView.get_context_data method of your WizardView subclass.

Here's a full example template:

{% 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 %}

Note

Note that {{ wizard.management_form }} must be used for the wizard to work properly.

Hooking the wizard into a URLconf

WizardView.as_view()

Finally, we need to specify which forms to use in the wizard, and then deploy the new WizardView object at a URL in the urls.py. The wizard's as_view() method takes a list of your ~django.forms.Form classes as an argument during instantiation:

from django.conf.urls import url

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

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

You can also pass the form list as a class attribute named form_list:

class ContactWizard(WizardView):
    form_list = [ContactForm1, ContactForm2]

Using a different template for each form

As mentioned above, you may specify a different template for each form. Consider an example using a form wizard to implement a multi-step checkout process for an online store. In the first step, the user specifies a billing and shipping address. In the second step, the user chooses payment type. If they chose to pay by credit card, they will enter credit card information in the next step. In the final step, they will confirm the purchase.

Here's what the view code might look like:

from django.http import HttpResponseRedirect
from 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/')
        ...

The urls.py file would contain something like:

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

The condition_dict can be passed as attribute for the as_view() method or as a class attribute named condition_dict:

class OrderWizard(WizardView):
    condition_dict = {'cc': pay_by_credit_card}

Note that the OrderWizard object is initialized with a list of pairs. The first element in the pair is a string that corresponds to the name of the step and the second is the form class.

In this example, the ~django.views.generic.base.TemplateResponseMixin.get_template_names() method returns a list containing a single template, which is selected based on the name of the current step.

Advanced WizardView methods

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 <form-prefix>.

WizardView.get_form_initial(step)

Returns a dictionary which will be passed as the ~django.forms.Form.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 ~django.forms.ModelForm is used as the form for step step.

Returns an ~django.db.models.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
• wizard -- a dictionary representation of the wizard instance with the following key/values:
  • form -- ~django.forms.Form or ~django.forms.formsets.BaseFormSet instance for the current step
  • steps -- A helper object to access the various steps related data
  • management_form -- all the management data for the current step

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

1.0

The request parameter was added.

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. If you override get_form, however, you will need to set step yourself using self.steps.current as in the example below. 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)

    # determine the step if not given
    if step is None:
        step = self.steps.current

    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 ~django.forms.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_goto_step(step, goto_step, **kwargs)

This method is called when the step should be changed to something else than the next step. By default, this method just stores the requested step goto_step in the storage and then renders the new step.

If you want to store the entered data of the current step before rendering the next step, you can overwrite this method.

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 ~django.forms.Form objects can be provided using the optional ~WizardView.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 ~django.forms.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.

The initial_dict can also be added as a class attribute named initial_dict to avoid having the initial data in the urls.py.

Handling files

WizardView.file_storage

To handle ~django.forms.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 ~django.core.files.storage.Storage subclass.

Django provides a built-in storage class (see the built-in filesystem storage class <builtin-fs-storage>):

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'))

Warning

Please remember to take care of removing old temporary files, as the WizardView will only remove these files if the wizard finishes correctly.

Conditionally view/skip specific steps

WizardView.condition_dict

The ~WizardView.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 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 url

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

contact_forms = [ContactForm1, ContactForm2]

urlpatterns = [
    url(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 ~WizardView.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 <django.forms.models> and ModelFormSets <model-formsets>. Additionally to ~WizardView.initial_dict, the ~WizardView.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

NamedUrlWizardView is a WizardView subclass which adds named-urls support to the wizard. This allows you to have separate URLs for every step. You can also use the NamedUrlSessionWizardView or NamedUrlCookieWizardView classes which preselect the backend used for storing information (Django sessions and browser cookies respectively).

To use the named URLs, you should not only use the NamedUrlWizardView instead of WizardView, but you will also have to change your urls.py.

The ~WizardView.as_view method takes two additional arguments:

• a required url_name -- the name of the url (as provided in the urls.py)
• an optional done_step_name -- the name of the done step, to be used in the URL

This is an example of a urls.py for a contact wizard with two steps, step 1 named contactdata and step 2 named leavemessage:

from django.conf.urls import url

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 = [
    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})