1 """

     2 Formtools Preview application.

     3 """

     4 

     5 import cPickle as pickle

     6 

     7 from django.conf import settings

     8 from django.http import Http404

     9 from django.shortcuts import render_to_response

    10 from django.template.context import RequestContext

    11 from django.utils.hashcompat import md5_constructor

    12 from django.contrib.formtools.utils import security_hash

    13 

    14 AUTO_ID = 'formtools_%s' # Each form here uses this as its auto_id parameter.

    15 

    16 class FormPreview(object):

    17     preview_template = 'formtools/preview.html'

    18     form_template = 'formtools/form.html'

    19 

    20     # METHODS SUBCLASSES SHOULDN'T OVERRIDE ###################################

    21 

    22     def __init__(self, form):

    23         # form should be a Form class, not an instance.

    24         self.form, self.state = form, {}

    25 

    26     def __call__(self, request, *args, **kwargs):

    27         stage = {'1': 'preview', '2': 'post'}.get(request.POST.get(self.unused_name('stage')), 'preview')

    28         self.parse_params(*args, **kwargs)

    29         try:

    30             method = getattr(self, stage + '_' + request.method.lower())

    31         except AttributeError:

    32             raise Http404

    33         return method(request)

    34 

    35     def unused_name(self, name):

    36         """

    37         Given a first-choice name, adds an underscore to the name until it

    38         reaches a name that isn't claimed by any field in the form.

    39 

    40         This is calculated rather than being hard-coded so that no field names

    41         are off-limits for use in the form.

    42         """

    43         while 1:

    44             try:

    45                 f = self.form.base_fields[name]

    46             except KeyError:

    47                 break # This field name isn't being used by the form.

    48             name += '_'

    49         return name

    50 

    51     def preview_get(self, request):

    52         "Displays the form"

    53         f = self.form(auto_id=AUTO_ID)

    54         return render_to_response(self.form_template,

    55             {'form': f, 'stage_field': self.unused_name('stage'), 'state': self.state},

    56             context_instance=RequestContext(request))

    57 

    58     def preview_post(self, request):

    59         "Validates the POST data. If valid, displays the preview page. Else, redisplays form."

    60         f = self.form(request.POST, auto_id=AUTO_ID)

    61         context = {'form': f, 'stage_field': self.unused_name('stage'), 'state': self.state}

    62         if f.is_valid():

    63             self.process_preview(request, f, context) 

    64             context['hash_field'] = self.unused_name('hash')

    65             context['hash_value'] = self.security_hash(request, f)

    66             return render_to_response(self.preview_template, context, context_instance=RequestContext(request))

    67         else:

    68             return render_to_response(self.form_template, context, context_instance=RequestContext(request))

    69 

    70     def post_post(self, request):

    71         "Validates the POST data. If valid, calls done(). Else, redisplays form."

    72         f = self.form(request.POST, auto_id=AUTO_ID)

    73         if f.is_valid():

    74             if self.security_hash(request, f) != request.POST.get(self.unused_name('hash')):

    75                 return self.failed_hash(request) # Security hash failed.

    76             return self.done(request, f.cleaned_data)

    77         else:

    78             return render_to_response(self.form_template,

    79                 {'form': f, 'stage_field': self.unused_name('stage'), 'state': self.state},

    80                 context_instance=RequestContext(request))

    81 

    82     # METHODS SUBCLASSES MIGHT OVERRIDE IF APPROPRIATE ########################

    83 

    84     def parse_params(self, *args, **kwargs):

    85         """

    86         Given captured args and kwargs from the URLconf, saves something in

    87         self.state and/or raises Http404 if necessary.

    88 

    89         For example, this URLconf captures a user_id variable:

    90 

    91             (r'^contact/(?P<user_id>\d{1,6})/$', MyFormPreview(MyForm)),

    92 

    93         In this case, the kwargs variable in parse_params would be

    94         {'user_id': 32} for a request to '/contact/32/'. You can use that

    95         user_id to make sure it's a valid user and/or save it for later, for

    96         use in done().

    97         """

    98         pass

    99 

   100     def process_preview(self, request, form, context):

   101         """

   102         Given a validated form, performs any extra processing before displaying

   103         the preview page, and saves any extra data in context.

   104         """

   105         pass

   106 

   107     def security_hash(self, request, form):

   108         """

   109         Calculates the security hash for the given HttpRequest and Form instances.

   110 

   111         Subclasses may want to take into account request-specific information,

   112         such as the IP address.

   113         """

   114         return security_hash(request, form)

   115 

   116     def failed_hash(self, request):

   117         "Returns an HttpResponse in the case of an invalid security hash."

   118         return self.preview_post(request)

   119 

   120     # METHODS SUBCLASSES MUST OVERRIDE ########################################

   121 

   122     def done(self, request, cleaned_data):

   123         """

   124         Does something with the cleaned_data and returns an

   125         HttpResponseRedirect.

   126         """

   127         raise NotImplementedError('You must define a done() method on your %s subclass.' % self.__class__.__name__)