from functools import wraps
from urlparse import urljoin
from uuid import uuid4
from django.http import *
from django.shortcuts import render_to_response
from django.template.context import RequestContext
from merlin.wizards.utils import *
def modifies_session(func):
@wraps(func)
def wrapper(self, request, *args, **kwargs):
result = func(self, request, *args, **kwargs)
request.session.modified = True
return result
return wrapper
[docs]class SessionWizard(object):
"""
This class allows for the ability to chop up a long form into sizable steps
and process each step in sequence. It also provides the ability to go back
to a previous step or move on to the next step in the sequence. When the
wizard runs out of steps it calls a final function that finishes the form
process. This class should be subclassed and the subclass should at a
minimum override the ``done`` method.
.. versionadded:: 0.1
:param steps:
Provides a list of :class:`Step` objects in the order in
which the wizard should display them to the user. This list can
be manipulated to add or remove steps as needed.
"""
def __init__(self, steps):
if not isinstance(steps, list):
raise TypeError('steps must be an instance of or subclass of list')
if [step for step in steps if not isinstance(step, Step)]:
raise TypeError('All steps must be an instance of Step')
slugs = set([step.slug for step in steps])
# By putting the slugs into a set the duplicates will be filtered out.
# If the slug list length does not equal the steps length then there
# must have been duplicates.
if len(slugs) != len(steps):
raise ValueError('Step slugs must be unique.')
self.id = str(uuid4())
self.base_steps = steps
def __call__(self, request, *args, **kwargs):
"""
Initialize the step list for the session if needed and call the proper
HTTP method handler.
"""
self._init_wizard(request)
slug = kwargs.get('slug', None)
step = self.get_step(request, slug)
if not slug:
raise Http404()
if not step:
raise Http404()
try:
method_name = 'process_%s' % request.method
method = getattr(self, method_name)
return method(request, step)
except AttributeError:
raise Http404()
def _init_wizard(self, request):
"""
Since the SessionWizard can be used as the callable for the urlconf
there will be only one instance of the class created. We need to
make sure each session has its own copy of the step list to manipulate.
This way multiple connections will not trample on each others steps.
"""
if self.id not in request.session:
request.session[self.id] = WizardState(
steps=self.base_steps[:], # Copies the list
current_step=self.base_steps[0],
form_data={})
def _get_state(self, request):
"""
Returns the :class:`WizardState` object used to manage this
wizards internal state.
"""
return request.session[self.id]
def _show_form(self, request, step, form):
"""
Render the provided form for the provided step to the
response stream.
"""
context = self.process_show_form(request, step, form)
return self.render_form(request, step, form, {
'current_step': step,
'form': form,
'previous_step': self.get_before(request, step),
'next_step': self.get_after(request, step),
'url_base': self._get_URL_base(request, step),
'extra_context': context
})
def _set_current_step(self, request, step):
"""
Sets the currenlty executing step.
"""
self._get_state(request).current_step = step
return step
def _get_URL_base(self, request, step):
"""
Returns the base URL of the wizard.
"""
index = request.path.find(step.slug)
return request.path[:index]
[docs] def process_GET(self, request, step):
"""
Renders the ``Form`` for the requested :class:`Step`
"""
form_data = self.get_cleaned_data(request, step)
if form_data:
form = step.form(initial=form_data)
else:
form = step.form()
return self._show_form(request, step, form)
[docs] def process_POST(self, request, step):
"""
Processes the current :class:`Step` and either send a redirect to the
next :class:`Step` in the sequence or finished the wizard process
by calling ``self.done``
"""
form = step.form(request.POST)
if not form.is_valid():
return self._show_form(request, step, form)
self.set_cleaned_data(request, step, form.cleaned_data)
self.process_step(request, step, form)
next_step = self.get_after(request, step)
if next_step:
url_base = self._get_URL_base(request, step)
return HttpResponseRedirect(urljoin(url_base, next_step.slug))
else:
response = self.done(request)
self.clear(request)
return response
[docs] def get_steps(self, request):
"""
Returns the list of :class:`Step`s used in this wizard sequence.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
"""
return self._get_state(request).steps
[docs] def get_step(self, request, slug):
"""
Returns the :class:`Step` that matches the provided slug.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
:param slug:
The unique identifier for a particular :class:`Step` in the
sequence.
"""
steps = self.get_steps(request)
try:
return [step for step in steps if step.slug == slug][0]
except IndexError:
return None
[docs] def get_before(self, request, step):
"""
Returns the previous :class:`Step` in the sequence after the provided
:class:`Step`. This function will return ``None`` if there is no
previous step.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
:param step:
The :class:`Step` to use as an index for finding the next
:class:`Step`
"""
steps = self.get_steps(request)
index = steps.index(step)
if index > 0:
return steps[index - 1]
else:
return None
[docs] def get_after(self, request, step):
"""
Returns the next :class:`Step` in the sequence after the provided
:class:`Step`. This function will return ``None`` if there is no
next step.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
:param step:
The :class:`Step` to use as an index for finding the next
:class:`Step`
"""
steps = self.get_steps(request)
index = steps.index(step)
try:
return steps[index + 1]
except IndexError:
return None
@modifies_session
[docs] def remove_step(self, request, step):
"""
Removes step from the wizard sequence.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
:param step:
The :class:`Step` to remove.
"""
steps = self.get_steps(request)
if step in steps:
steps.remove(step)
@modifies_session
[docs] def insert_before(self, request, current_step, step):
"""
Inserts a new step into the wizard sequence before the provided step.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
:param current_step:
The :class:`Step` to use as an index for inserting a new step
:param step:
The new :class:`Step` to insert.
"""
steps = self.get_steps(request)
if step not in steps:
index = steps.index(current_step)
steps.insert(index, step)
@modifies_session
[docs] def insert_after(self, request, current_step, step):
"""
Inserts a new step into the wizard sequence after the provided step.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
:param current_step:
The :class:`Step` to use as an index for inserting a new step
:param step:
The new :class:`Step` to insert.
"""
steps = self.get_steps(request)
if step not in steps:
index = steps.index(current_step) + 1
steps.insert(index, step)
[docs] def get_cleaned_data(self, request, step):
"""
Returns the cleaned form data for the provided step.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
:param step:
The :class:`Step` to use to pull the cleaned form data.
"""
return self._get_state(request).form_data.get(step.slug, None)
@modifies_session
[docs] def set_cleaned_data(self, request, step, data):
"""
Sets the cleaned form data for the provided step.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
:param step:
The :class:`Step` to use to store the cleaned form data.
:param data:
The cleaned ``Form`` data to store.
"""
self._get_state(request).form_data[step.slug] = data
[docs] def clear(self, request):
"""
Removes the internal wizard state from the session
"""
del request.session[self.id]
# METHODS SUBCLASSES MIGHT OVERRIDE IF APPROPRIATE ########################
[docs] def process_step(self, request, step, form):
"""
Hook for modifying the ``SessionWizard``'s internal state, given a fully
validated ``Form`` object. The ``Form`` is guaranteed to have clean,
valid data.
This method should *not* modify any of that data. Rather, it might want
dynamically alter the step list, based on previously submitted forms.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
:param step:
The current :class:`Step` that is being processed.
:param form:
The Django ``Form`` object that is being processed.
"""
pass
[docs] def get_template(self, request, step, form):
"""
Responsible for return the path to the template that should be used
to render this current form.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
:param step:
The current :class:`Step` that is being processed.
:param form:
The Django ``Form`` object that is being processed.
"""
return 'forms/wizard.html'
[docs] def done(self, request):
"""
Responsible for processing the validated form data that the wizard
collects from the user. This function should be overridden by the
implementing subclass. This function needs to return a ``HttpResponse``
object.
:param request:
A ``HttpRequest`` object that carries along with it the session
used to access the wizard state.
"""
raise NotImplementedError("Your %s class has not defined a done() " \
"method, which is required." \
% self.__class__.__name__)